A word which means the same as 'awesome', except that by adding 'possum' at the end it sounds waaaay more awesome. Just because it rhymes. Contrary to its name, it has nothing to do with possums at all, and is just there to make it sound more interesting e.g. Liar liar, pants on fire.
Zak: "Hey dude, do you remember Sisqo's Thong Song?"
Caleb: "Yeah man, awesome video eh?"
Zak: " "Yeah man. Awesome possum!"