My favorite example at the moment is “U2”. If the first thing you think of is:
A plane: You’re over 55.
A band: You’re 30-55.
Textspeak for “you too”: You’re under 30.
“Gay” is sort of similar. If the first thing you think of is:
Happy: You’re over 70.
Homosexual: You’re 30-70.
Lame: You’re under 30.
(I may have the cut points wrong, but you get the idea.)
I have the feeling that most examples will be everyday words that have become slang at some point, and most of the rest will have to do with changes in culture or technology. (Ex.: Is a tablet something you swallow, or something you look at?)
If you’re over 30 and you say “That’s sick!” you probably have a disgusted grimace on your face.
If you’re under 30 and you say “That’s sick!” you probably have wide eyes and a big grin.
One I find funny is “Do you live at home?” which means something different for people, say, 17-25 than for anyone else. For everyone else, that is a tautology.
I’ve heard of all these except bomb. I’d call it a sub, but hoagie or grinder come easily to me. Bomb, however, is completely new to me. I’m 31 and from upstate NY, live in Ohio. A bomb would be the thing in wars, and I do know it’s slang for good, ie “that’s da bomb”.
Sub, Hoagie, Hero, Grinder, Po’boy - I think of a sandwich. Bomb - I think of an explosive, or possibly “that’s the bomb” meaning “that’s cool”, or possibly “bomb” as in not doing well at the box office or getting bad reviews. I’ve never heard it used to mean a sandwich.
I’m in the 35-59 range.
I’ve only encountered it a few times. A sandwich shop in one of the larger towns near my backwater Louisiana home offered a “Swamp Bomb” sandwich, which was a sort of sweep-the-kitchen poboy. I’ve also run into the term “burger bomb” a few times. My limited experience suggests that it carries a connotation of a big sandwich with lots of ingredients or toppings, on a bun or roll. It’s not a term I would immediately associate with a sandwich without some sort of context.
In Fredonia, NY, there was a sub shop called The Bomber House. I thought it was a nonce using but apparently there are other places, even with that exact same name. They made a pretty good cheesesteak, too.