I would have a joke for my friend... but he can't afford the punchline.
Unaffordable Punchline
Explanation
Explain Bear
Listen up, buttercup. The joke is that the dude's friend is so broke, he can't even "afford" the punchline. It's a play on words, see? Like, jokes cost money now, which they don't, ya dummy! You probably still use a rotary phone, huh?