When you are sitting in a chair and your cat makes an attempt to jump into your lap but realizes there is no room and has to jump off quickly. Usually this is because you have a laptop computer, magazine or plate of food, etc. already taking up that space.
Spouse 1: Jeez! The cat just tried to jump right into my lap and I didn't even invite him up here.
Spouse 2: Ha ha! Lap-blocked!