The first part of your post had me holding my breath...then peeing myself! As far as the 'humping' behaviour, it's usually a dominance thing, not sexual in anyway. I'd ignore it. Peeing is a whole other can of worms! If it was a one time incident then chances are it was drug induced...catnip frenzy! Be sure to clean the wet areas up with a good cleaner, that won't leave urine scent behind. White vinegar works well, and is cheap, but the majority of the pee should be blotted up first. Then saturate the areas with the vinegar and let it air dry. Hopefully such nawty behaviour won't be repeated!