Puns are all about the ‘sell’. If I think of a particularly bad one, I don’t hold back. I just follow it up with an over-the-top routine of “Get it? Get it? Huh? Do you?” and as they insist that they do in fact get it, I just keep bombarding “You sure? All of it? Because I could totally explain it if you want me to.” i don’t want them to laugh at the pun, I want them to laugh at me.
There’s always the second approach of throwing it out there, and then placing a hand on the eye-rolling subject’s shoulder, and sympatheticly and with great concern go “It was just a little joke to make you smile, it’s ok, really.” like I’m concerned that they’re depressed cause they’re not laughing…it’s them, not me. That usually elicits a smile.
My latest victim was my English Lit teacher. He mentioned Androcles (who pulled the thorn from a lion’s paw) and said “It’s possible that the author is alluding to Androcles…” and I jump in “It’s paaaaw-sible?” Hilarity ensued.
God, I love a good pun. But I can’t watch the news, because they’re always trying to tie the headlines into some sort of pun-knot that really makes me want a sharp object.
There was an Isaac Asimov story which dealt with puns (not Shah Guido G., also readable as “Shaggy Dog,” or a story with the punchline as a pun, as linked by bouv)
Scientists had come up with a theory that all jokes were of extraterrestrial origin, as they seem to inundate the globe at all places at once. Furthermore, whenever a lowly Homo sapiens tries to make a joke, it’s actually a pun, and not truly funny.
Once they determined that jokes were alien, they had to figure out why.
Humor was an alien experiment. But, as with all experiments, once the subjects are aware they are being tested, the experiment ends, and a new one begins.
The story ended with one scientist telling the funniest joke he knew, one that always got a laugh…
But humor had been taken away from us, no longer to find anything funny.
Then I bet you’ll love this one (not actually a pun, but in the same vein of humor, I think).
To everyone who didn’t place me on their ignore lists for that, thank you. 
(Oh, and thanks to drewbert and Wile E for reminding me exactly what kind of pain I was talking about.) 
I agree with the comments that someone who’s always trying to shoehorn puns into a conversation is obnoxious, but then that’s just bad joke-telling, and, really, no good can come of that.
The part that’s always confused me and prompted the birth of this thread (besides the opportunity to inflict that pun upon others) was why puns are almost invariably “groaners.” No matter how organic, how well-told, how well-timed, a pun draws a groan instead of a laugh.
Personally, I think AHunter3 has it right when he says it’s the feeling of being “had,” but I’ll continue to ponder the matter…
Just don’t try and hold me responsible for the physical harm that’s sure to be inflicted upon you…
And, just because… (A true story this time.)
I was walking through a Best Buy (why always Best Buy? I don’t know.) with AudreyK one day, and, as Best Buy tends to do, they had a pile of Aquos LCD TVs stacked in the middle of the aisle with a price tag atop it.
As we approaced them, I quickly grabbed AudreyK by the shoulders and moved her aside.
“Careful, those TVs are Sharp!”