Anything that can be penetrated with a penis, including:

vaginas, ani (anuses), mouths, tightly closed armpits, squeezed together breasts, holes in the walls of public toilets, wounds, empty eye sockets, flesh lights, nostrils, ear holes, pushed together feet, warm pies, ripe fruit, bin bags, two-week old corpses, animal cages and sauce bottle with the lids removed.

It should be noted that most of these are not reccomended in any way, shape or form.
"That girl had more penetrateables than a two-week dead pirate."
by H.S. Willsy August 23, 2011
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