It definitely happens out on the ramp occasionally. I think some of them are intentional and some are not...you can usually tell by the demeanor of the pilots before they get on the plane.

One time I was pushing back an RJ and a maintenance crew on board an MD90 across the way thought it would be a good idea to do a run up at the gate. I ended up getting off the tug and hiding behind it until it was over. Needless to say maintenance got in trouble for that one.

Best advice, keep you head up and aware, and report it to ops. if you think it was intentional. The pilot(s) might think its a good idea until a piece of FOD impales a person.