to have sex like a wild horny beast.

A phrase to describe someone who is cognitively degenerating. Synonym of "going off the deep end". Can have varying degrees of severity.

Reference to the song "Hey You" by Pink Floyd. The line "and the worms ate into his brain" makes no sense in an otherwise linear and literal narration throughout the lyrics.

When you're fucking someone with such tenacity that they (and most likely you) lose the ability to formulate words or thoughts having to do with anything besides getting fucked harder, thus at the level of dumb BEASTS.

when you have sex with a chick like you havn't fucked in a decade.

To have sexual intercourse with someone repugnant, usually in such a way as to avoid looking at them.