An invitation to someone's bed to get busy (from the wooden slats of the bed frame.) Often used in a situation where nothing else is desired but a casual encounter but the user wants to use a term less obvious than 'booty call'.
Also, a thorough investigation of some chic's ass.
Yo, I'll be over around 10ish or whenever I finish the slat tour.
I wasn't going to try to get in her pants until after dinner, but then she offered me the full slat tour.