Tim, bringing sick Jill a selection of "doctor" themed movies: "Dr. No, Doctor Dolittle, Doctor Naughty and the Night Nurses... oops."
From the same episode, "Super Bowl Fever":
Mark: Mom's really sick! She keeps moaning really loud and calling your name!
Tim: Always my dream.
The episode "The Naked Truth", when Tim accidentally sees his sister-in-law in the shower, is full of this.
From the pilot:
Jill: Tim, do you ever listen to me? It was the last thing that I said in bed to you last night.
Tim: No, I believe, if you recall, the last thing you said to me in bed last night was "no!"
Jill: You're thinking of tonight.
From "Satellite on a Hot Tin Roof":
Jill: Tim, what do you actually know about installing a satellite dish?
Tim: It's simple. Mount it, point it straight up. Any man could do that.
Jill: Yeah, but it has to stay up longer than ten seconds.
After a night of making up...
Mark: Brad and Randy told me what you were doing last night. Jill: ...they did? Mark: Yeah! Who won the somersault competition? Tim: ...your mom. Mark: Yay mom! (Mark leaves) Tim: You did win, didn't you? Jill: Yeah. Twice.