We worked it out with Satanael - when you prime nade (just don't prime for too long, only click and release) and throw it onto the ground, so that it comes to stop, your opponent can walk through it and it will disappear. There can't be more than one grenade thrown, it most likely has to be primed nade (timed didn't work or worked once), and it has to be walked onto, not jumped. Given these circumstances, if there is still a little time to explode, you can almost always perform this glitch. Ticking timebomb would work, with normal explode time one couldn't walk more than few units before exploding.
Demo for reference attached.