age dropping
A concept related to that of name dropping. But instead of dropping the name of famous people you know, you drop the age of the (sexual) partners you`ve had in order to impress friends.
A(male, age 18): Dude! I`ve just been with a 26 year old woman!
B: That´s got to be a lie! I call you´re age dropping!
B: That´s got to be a lie! I call you´re age dropping!