The act of one person taking a dump normally on a toilet while another person sits on their lap facing them and takes a dump through the space between the first persons legs.
A tandump can be performed either consensually or by ambush. In an ambush tandump, the assailant initiates a tandump by climbing over a stall wall and dropping down onto the unsuspecting pooper.
Ari: Hey Jacob, wanna take a tandump with me??
Jacob: Yeah of course! I call dibs on bottom!
************
Joe: Mike, why did you and Elaina break up?!?
Mike B: Her ex, Josh, told me that she really enjoyed tandumps, so I decided to surprise her with an ambush tandump! She threw up on me and threatened to call the police...
A technique in which friends cross arms, and use eachothers weight too lean back, and pooh, when no sign of tiolet is in view. This technique is mainly used in the woods, where the secret cannot be released to society. Group poohs can also take place, if there is more then two friends in desperate need of relaseing a giant alejandro.