A teacher was wrapping up class, and started talking about tomorrow's 
final exam. He said there would be no excuses for not 
showing up tomorrow, barring a dire medical condition or an immediate 
family member's death. 

One smart ass student said, "What about extreme sexual exhaustion?", 
and the whole classroom burst into laughter. After the laughter had 
subsided, the teacher glared at the student, and said, "Not an excuse,
you can just use your other hand to write."

My wife used to have the habit of disbelieving something with 
the phrase "my ass!"  She would say "Four hundred dollars, 
my ass!" or "30 minutes late, my ass!"  One day a friend of 
mine and I were having a conversation, which she was listening 
to, and I said something like "...so it would be easy to 
penetrate.."  She chimed in... "Penetrate my ass!"  My friend 
and I laughed so long and hard we forgot what we were even 
talking about!  Needless to say, she doesn't say "my ass!" any 
more.

While my wife and I were shopping at a mall kiosk, a shapely young
woman in a short, form-fitting dress strolled by. My eyes followed.
Without looking up from the item she was examining, my wife asked,
"Was it worth the trouble you're in?"