Ribald and forgo

"You know, you could go without the lewd jokes for one night."
"What, so your mom will be impressed?"
"No, just because I'm tired of hearing them. It's the same ones all the time."
"That's not true! I add a new one every day."
"Every day? Yeah right."
"Seriously. I'm on a mailing list. I get them sent to me."
"Oh, well that's original."
"Hey, I never claimed to make them up myself. It's not like they're less funny if they're someone else's."
"No, but it's hard to be less funny when they're not funny to begin with."
"Why are you always so negative?"
"Why are you always so crude?"
[silence]
"I'll be polite if you'll be positive."
"Hah. I give that a day."
"That was still negative."