A cheek buster is when you blow up your cheeks whilst biting down on your lips. Blowing them up and blowing them up as much as you can makes it a cheek buster. To the max!
I'll get you good you pesky ant! *cheek buster*
The act of putting one's penis into the mouth of a woman and stretching her mouth cheek so that you can see the outline of the penis within the cheek. If done repeatedly, could be called "cheek-fucking".
"Yo! I did a cheek buster(s) on her last night and spewed it onto her face...."