Prepare cake mixes and bake according to package directions (any size pan).
Prepare pudding according to package directions and chill until ready to assemble.
Crumble sandwich cookies in small batches in a food processor, scraping often.
When cakes are cooled to room temperature, crumble them into a large bowl. Toss with 1/2 of the remaining cookie crumbs, and the chilled pudding. You probably won't need all of the pudding, you want the cake to be just moist, not soggy.
Put cake mixture into a clean, washed (never used, please) litter box.
Put half of the unwrapped tootsie rolls in a microwave safe dish and heat until softened. Shape the ends so that they are no longer blunt, and curve the tootsie rolls slightly. Bury tootsie rolls randomly in the cake and sprinkle with half of the remaining cookie crumbs.
Heat the remaining tootsie rolls until pliable and shape as before. Spread all but one randomly over top of cake mixture. Sprinkle with any remaining cookie crumbs. Hang the remaining tootsie roll over side of litter box and sprinkle with a few cookie crumbs. Serve with the pooper scooper.