A somewhat self explanatory question, what makes mess in a big red nose fun for you?
Personally, I adore the goofiness of it, it's fun to let loose by laughing. Eve adding gags or self inflicted booby traps before a slopping, fun stuff like that! As well as that, making a big show out of the slop is fun as well, whether it be performative grossness or jamming up the delivery!
The entire thing is just completely ridiculous and wacky, which can make it really funny to see or be a part of. I also like knowing that it can make others laugh for a little bit.
Not to mention that once you get hit with the first pie, you are already humiliated so you may as well go all out being goofy and over the top and take all the pies you can.