Morning splinter 

Morning wood in the less well endowed.

I woke up but couldn't go outside because of an embarrassing case of morning splinter.

Morning splinter by The Etymologist March 20, 2009

morning splitter 

In males, the early morning piss in which the stream tends to split into at least a couple different directions; in the most extreme cases, this can cause a good bit of piss to end up on the rim of the toilet bowl

Damn this morning splitter. I don't have time to be wipin piss off the rim of the toilet today.

morning splitter by @$$Y McGee April 13, 2008