Gag on sweaty socks then clean dirty trainers

Foxtress has some brand new Pleaser Boots. She also has a pair of dirty, well worn, battered, old, manky, trainers. To decide which he gets, Foxtress has a simple and fun game. She will place her foot in his mouth. If he can keep it there for 15 seconds without gagging or spitting her foot out it's the boots, if he fails it's the trainers.