slang term for a child seat as the slang term for a baby is trophy
Girl: Did you hear Heather had a baby?
Guy: I figured after I seen a trophy case in the back of her Honda.
Being so impressed and proud of the prize winning turd you've just layed to rest in the crapper, that you leave the cubicle without flushing and wipe your arse in the next one. Leaving your 'dead otter' for the next visitor to enjoy.
Oh man, I just went upstairs to drop a protein submarine and someone had left a trophy case for me!