Toaster blocks are special blocks found in the later levels of Battleblock Theater. They dispense large, walking pieces of toast, which will attack any players who get too close. While their attacks can't directly kill the player, their large knockback can wind up throwing them into a hazard.
The toast enemy can't be killed by punching, but it can be drowned, impaled on spikes, cut with a saw, or set on fire by a Fireball or laser. Once it dies, the toaster will create another toast enemy, though there can only be one toast enemy active at a time per toaster.
If the player somehow blocks the top of the toaster (by using a movable block or a rock; standing on top will not work), then the toaster won't be able to create any more toast until the blockage is removed.