The halloween crit-boost pumpkin pickup is a weird version of a tf_ammo_pickup, and cannot be manually created, nor is included in any FGD. This is a prefab mimicking it with a small ammo kit, a trigger, a prop_dynamic, and an ambient_generic. It acts similarly to the normal pumpkins, and can even be picked up (with sound!) when the player is full on ammo. It will completely delete itself on pickup.