When Terry goes to Allen's home, they talk about the movie She's Got Mail (You've Got Mail) casting Tom Hanks and Meg Ryan. Allen said Tom Hanks have poison ivy up his ass. What's he talking about?
The line from the movie is:
It was like that movie where Meg Ryan meets that guy with poison ivy in his ass... I'll think of the name later...
This comparison is a dissimile, presumably added as a joke - there was no poison ivy in You've Got Mail and this is covered later when they remember the name of the movie:
"She's Got Mail", that's the name of the movie. - That's it!
With Tom Hanks? - And Meg Ryan. - He didn't have poison ivy up his ass.