One can use any type of oil to get messy in, from cooking oil to baby oil and it's not too smelly if you get non-vegetable oil. It feels sticky, gives good cover and shows a wetlook shine to any garments or even naked skin. You can buy it anywhere in any amount and not look like you're shopping for WAM supplies. It's easy to clean up after with a bit of soapy water and is usually used in inflatable pools or bathed in. It can be reused for a few photo shoots, but be careful not to slip! :)

A critical safety reminder for those who intend to wash and reuse their oily clothing: never put it in the clothes dryer for risk of fire! Wash it separately (and possibly more than once) so the oil does not saturate other clothing and then line-dry, outdoors or in. Even clothing that is merely stained with oil, as opposed to being saturated, should receive this treatment as it contains a flammable substance.

Some of the best oils you can also buy in bulk and last the longest because you don't need that much of it to be both effective and lasting.