I think a molt roostertail is a can with petrol in it, and a rag drenched in petrol hanging out of it. With other words: a bomb.
no, it is a (best one to use) Liquor bottle, a liquor with a good amount of alcohol in it (Captain Morgan is recommended), drench a rag (like a cloth) in it, have half hang out, light that half, and throw it. The rag will catch on fire, and when the bottle breaks, alcohol will splatter everywhere and burn in flames, causing a fiery explosion. It looks cool, but only a dummy would actually mess with one (OK i admit, i tried once and just burnt my hand)