When you have anal intercourse while using rubbing alcohol as lubricant. The giving party then takes a lighter and lights the receiving party's b-hole on fire.
When someone is asleep, you proceed to defecate, vomit, urinate, and blow your load on their hair. Then you mix it all together, in the same way you would shampoo your hair. After that you proceed to light it on fire, hence "baked" alaskan pie.
When Travis fell asleep last night Igor snuck into his room with a book of matches, a full bladder, lotion, and a gag stick, while prairy dogging his poop. He had all the tools needed to continue to make himself a Baked Alaskan Pie.
A sexual act that involves defecating on the partner's chest, ejaculatingon top of it, and flatulating over an open source of flame to enlight the mound of excrement ablaze.
That big meal of fettucini just made me want to take her home and make a nice warm baked alaska all over her.