I... I'm sorry, I really can't narrow it down to one thing. Dead Rising may have a coherent story that seems somewhat grounded in reality, but in all other senses, there are so many absurd and wacky things to do throughout all three titles, you would think this was a parody game of sorts. To wit:
- Your protagonist - either Frank, Chuck, or Nick - has the potential to dress up in a variety of silly costumes and outfits, not limited to summer dresses, tube tops, Servbot heads and freakin' banana hammocks
- The various psychopaths (which serve as boss battles) that inhabit each game include a children's mascot on roller skates, a Bengal tiger, at least two gimps, and a large old lady on a mobility scooter
- Your arsenal consists of, among other things, toy Mega Busters, tennis rackets, katanas, a swordfish, REAL Mega Busters, and with the added ability of combining weapons from the second game onward, laser swords, electric wheelchairs and lizard masks stuffed with live fireworks
- You can, if you feel so inclined, absolutely mow over crowds of zombies on a tricycle
Really, just take your pick on this one. The Dead Rising franchise is essentially a whole buffet line of ridiculous, off-the-wall moments and features, and I've barely scratched the tip of the iceberg.