Fat as Mud

An old-timey saying indicating that something is extremely large.

Me: That dude is huge!
Someone’s grandpa: Yeah, he’s fat as mud.

mud rut

Having nothing but anal sex because your girlfriend is saving her vagina for marriage. It get's boring.

"Bro, I've been Mud Ruttin' with this girl for so long. I may have to pop the question just to get some pussy."