Birds, hehe.

Jack sits on the roof, sipping on some good-ass Mountain Dew. Grenades are placed on the other side by... someone

Ah.

A crow flies over the roof

Oh. Bird.

It swoops to the location of the grenades and grabs one of them, thinking it's a round rat, and flies in front of Jack, to the eastern wall.

Huh. Poor the guy who owned those.

The bird accidentally hits the wall, unpinning the grenade. After the bird recovers, the bomb explodes.

...okay