sideways piss Share definition Flag When a guy pisses on the side of the toilit just above the water. Usally done when they are drunk or want to be quite. Dude, I took a sideways piss last night but it ended up everywhere. sideways piss by sumdudeu4got December 8, 2009 0 0 Get merch Get the sideways piss mug. Buy Now — $32.95 See more merch