Spaw' do you really want an explanation? (Cause if you don't, I won't give it to you)I assume you're sincere, so here goes: A butt plug is a little(or not so little, depends on the recipient's taste) plug you stick up your a** in order to enhance sexual pleasure (I never said I used one!)
(Like a wee dildo stuck up the rear end.)
Let your imagination take over from here, and see if you can figure out how you would act if you had one. :)
Magpie