In snowboarding, grabbing tindy is a rather unpopular habit. A snowboarder grabs indy by gabbing the toeside of his board with his trailing hand. Ideally, the rider should grab in between the bindings, thus appearing to have a good deal of control, and grace in the trick.
However, if the grab is overly forced, or if the rider is out of control, or lacks confidence, he/she will probably just grab the toeside of the board wherever they can. If they do this, they'll probably grab in the region between the rear binding and the end of the tail. This is grabbing tindy (tail/indy).
Generally, it looks much worse, and you can usually spot a beginner or person who is out of control by looking at where they grab the board. If you grab in the same area, except on the heelside, when trying to do a stalefish, you are doing a tailfish. This is equally as reprehensible.