MC Hammer had a hit with the name "U Can't Touch This." Generally means "I'm too good for you." or "You'll never be as good as I am."
Two people are dancing:
Person 1: Can't touch this!
Person 2: Darn. (walks off the dance floor)
Originally used on the 90's TV show "Pinky and the Brain," in a three part episode where everyone would do a strange dance called the "schmeerskahoven."
Stick your finger in your belly,
Don't be afraid if it jiggles like jelly