Preemptive Block 

Blocking someone on a social networking site, hookup site or app before that person has ever had a chance to contact you.

Gay Guy A: Eww, look at that nasty old man!

Gay Guy B: Gross, he's so old he's like 35! Did he contact you?

Gay Guy A: No, I pulled a Preemptive Block before he could ever dare try to get with my hotness!

Gay Guy B: Nashty.

Preemptive Block by Larrold June 8, 2011

Preemptive cock-block 

The act of preventing interaction between one or more females with one or more men prior to any communication between the two groups, thereby negating the need to cock-block them later on, after they have started making moves on the women.

A: Hey man, how were those girls that Johnny showed up with?
B: I don't know, he sat down at a different table, so I couldn't talk to any of them.
A: Ah, dude, that was like a preemptive cock-block.

Preemptive cock-block by Swill128 June 21, 2009