Bathtub Tower defense is a Roblox game that is based off DaFuqBoom's Skibidi Toilet series on Youtube.
The main premise of the game is a Tower Defense game set around the Skibidi Toilet series, where the game starts you out with a basic Cameraman Unit, and you work your way up by winning matches to summon more units and play more matches or trade with other players to get better units.
Occasionally the developers will release limited time events (Eg, Easter) where you can get exclusive units that wont be available ever again once said event has finished.