Dog Whistle is a trinket in Potato Packs, a mod for The Binding of Isaac. It is part of the Potato Pack 4 submod.
Bum familiars are locked in place when entering a room, preventing them from collecting pickups. Pressing the drop input or CTRL button toggles their ability to move.
If Isaac collects a bum item and the whistle has not already appeared in the current run it will spawn nearby.
If Isaac has no bum items and uses the whistle he will be given a random bum item.
Part of the Potato Pack 4 mod.