Verb. To place ones boner in another's ass crack whilst engaging in the act of spooning.
Note: Boners may be had by both partners but it is important that the large spoon's boner be in the the little spoon's crack.
"It was really nice, we cuddled on the couch and watched Jersey Shore."
"So you didn't get ANY action?"
"No! We totally creased!"
"Oh, I love a good crease session."