This footage from Guangdong province, China, shows an army recruit learning how to throw a grenade. Summation: he sucks at it.
Instead of throwing the grenade over a protective wall, he drops it just a few feet away from where he and his instructor are standing.
The instructor, noting the problem, dives for a trench, pulling the recruit in with him. They both survive, apparently unharmed.
-via Daily Telegraph (warning: auto-start video)
1. This is common...
2. ... so common that they dug that pit specifically for that reason...
3. ... so common that the instructor is trained to have his hand on the trainee's belt specifically to get a secure grip on him to throw/pull them both down into the pit quickly.
The really rare thing here is that they actually got it on video.
It's a good thing they plan for these eventualities so thoroughly. BTW, the kill zone for a grenade is about 20-40 ft, so without that planning, they'd both be ground meat.