For me it usually goes:

Person: so you like anime
me: yeah I also like manga
Person: Whats manga
me: comic version of anime
Person: ....
Person: so do you read hentai?
me: no thats porn...
Person "_______" reads hentai!!!
another person: whats hentai?
Person: its porn
the other person looks at me weird
me: I dont!!!

or:

me do you like anime or manga?
person: I dont know what that is
me: its japanese comics 🙂
person: I dont care
me: its really cool though
person: you never shut up do you....
me:no....Its really cool though!!!

This is my Siggie.

Where I used to live, I had some friends who share my manga hobby and we all enjoyed it.

However, where I am now, people just go like, "You're wasting your time, dude." "Stop reading manga." "Can you do anything else?" I guess I'm kind of obsessed with manga, but they're so good, though people wouldn't even give it a thought.

Here's my attempt at suggesting manga to my friend:

Me: Do you read manga?
Friend: No, never.
Me: It's really good, you know?
Friend: ...really...
Me: You should give it a try! I can recommend some good titles!
Friend: ... you like weird stuffs...
Me: It's not that much different from a book, you know... -____-
Friend: No thanks, I'm not a fob anyway

... Conclusion: Only fobs read manga. Period. Tsk.

"True love is not about loving a perfect person but loving an imperfect person perfectly!"

"And then I met you. Because of you, I'm brave enough to be different."

"What is the use of intelligence when one lacks compassion for the life around oneself? What good is bravery when one doesn't recognize hope as the most powerful weapon of all? And what is the point of beauty, when one's heart isn't one's loveliest feature?"

~~ Just feel like inserting some quotes xD ~~

NIJIGEN HA JINRUI WO TSUKUU.

most of my friends already know what manga is. i remember sucking them in to this vortex by introducing them to bleach when it was still good (the save rukia arc, before the boundo or whatever they're called) 4/5 years ago.

now i tell them to read stuff like blade of the immortal and vagabond, and they love the stuff like i do.

these days i just play eroge from minato soft/type moon/nitro +

so my conversation with people generally isn't about manga: it's about eroge and it's godly stories.

me: hey man do you play eroge (people who call eroge visual novels lollolollo)
guy: wat no- wdf is eroge
me: its a hentai game. its pretty cool. "but i swear i only play it for the story"
guy: lulz im sure right. how do you even play them, what do you do
me: well really, it's just a book on your computer but its kinda like a choose your adventure thing, since you can choose what the main character does, like put it in, or put it in. looool
guy: oh wow dude.

me: ... but seriously the story is good you should read tsukihime some time.
guy: lol

Wow, I can't say that I ever run in problems with telling people about my hobby. In fact, they're often interested and want to know more. But I think about how to explain it based on the person in front of me. I also agree with someone before me who posted some posters here really don't deserve any better reaction if they give such stupid explanations...

Manga are part of my bachelor thesis. So I had to explain to my grandparents what I write about. My granny is 78 years old:

Granny: "So you write about Japanese people. Like samurai and such?"
Me: "Yes and no. I write about Japanese pop-culture and how it influences youth subcultures here in Germany."
Granny: "Hm, I don't understand. You mean Punks get influences by Japanese?"
Me: "No, I write e.g. about how Japanese comics became popular over here and how a whole youth scene developed around it."
Granny: "Oh, this is very interesting. Japanese comics, huh? You mean the picture books your sister reads?"
Me: "Yes exactly, and you remember the photos I showed you from the costume players? This is one of the scenes that fans of these comics created."
Granny: "Yes yes, this is very faszinating. These young people put so much creativity and effort into the costumes. I'm really impressed. You know when your uncles were little they were reading these American comics with Batman and Superman and weird monsters. I always found them dumb because they made your uncles run around with a bedsheet as cape >.>
The Japanese comics on the other hand seem to have a lot more depth. I'm not interested in trying to read one but I like a lot that they make young people learn sewing and handcraftig again."

I think it depends on how you explain things and to whom. I never used any confusing terms for my grandparents and stressed out things I know they'll like. My granny is pretty conservative and on this "girls should be good in sewing&cooking"-statement. So I told her about cosplay and how manga fans are interested in learning Japanese cooking (showed her Bento too).

If I'd overrun her with cliche manga fangirling, she would have never accepted that as a serious hobby. Now she even motivates my sister to work on her first cosplay and helps with the sewing and fabric stuff. It's just great. Brought the family generations closer together.

I'm a LARPer and my grandpa helped me fixing my weapons. He's 81 years and also very conservative. I needed to bring up a lot serious points to make him understand what I do there but now he sees it on the same creativity level as the mini train track he has in the cellar and helps me with 'technical' problems on my amour as well as with working on show fighting techniques, hehe ^^

Sorry, I'm Late.
But I Got Lost On The Road Of Life.

Ha ha what an interesting thread. I get the "mango" response too. I've finally managed to get my friends to understand what I mean when I say Manga and Anime. (I had a heated debate about the whole anime is not a cartoon with them xD)
Although I do sometimes get "are you going to read anime?" which always results in a palm to face.