You should be on that.

It's what a married guy says to a single guy when he sees an attractive female but realizes he can't do anything because he's married. However, he would really like to live vicariously through his single friend when said single friend hooks up with said female. He would also like to hear about the sexual activities so he has something to envision when he's with his fat wife.

Married guy to single guy: I saw that neighbor of yours with the Beagle and she's looking good. You should be on that.