Super Bum is a transformation in The Binding of Isaac, added in the Afterbirth DLC.
Obtained by holding Bum Friend, Dark Bum and Key Bum at the same time.
Combines all 3 aforementioned familiars into Super Bum who automatically collects all coins, red hearts and keys off the ground and drops twice as many rewards as the regular bums would have.
This also applies to items, as 2 items will be dropped whenever one would.
A unique animation plays when the transformation is acquired. See the video link below.
This page shows the latest information as of the new Repentance+ (Online Co-op) DLC.
To see information about this transformation for the previous Repentance version, check this page instead.