I'd gladly slap that butt whether your panties are full with foam or not, but -- since you've started to fill them, by all means carry on until they're full!
Looks like you also have filled up your bra with foam, and I'd happily give you a very messy motorboat along with the sloptastic spanking you are asking for!
Great action with the whipped cream...but you should give your hot guy an oil massage on a foil. From what I can see, he'll get so turned on by it that he'll squirt a huge load into your mouth, and not just once...