Any thick, creamy substance is a popular choice in the world of wam. Non-dairy whipped topping, however, is deceptive: It's oil-based, and has a lot of air whipped into it. When it warms with your body heat, the air escapes and the topping turns back into oil.
Whipped topping is a good alternative to real cream because there is less chance of a rancid smell being left on your skin after your wam. Also, it tends to be cheaper to buy.