I have one!
My DS is 16 months and has really hit the trantruming phase. If he is cross, unhappy, frustrated, or his will slighted in any way, he will crouch down and bang his head on the floor. (if he doesn't know how hard the floor surface is, he'll do it very very gently at first, giving the impression that this screeching banshee lunatic toddler is just interrupting this tantrum to pray to Mecca.)
The other day we went to the pool. There is a 50 metre lap pool, 2 metres deep at one end; a children's pool where all the lessons are, about 1 metre deep; and a toddler pool that's 30cm deep at one end and just covers your toes at the other end. DS, of course, toddled straight for the lap pool, the deep end no less, and was OUTRAGED when I scooped him up and took him to the toddler pool. Straight into tantrum mode, yelling, shrieking and going for the "whack my head on the floor" routine.
He got a mouthful of water and sat up coughing and spluttering and sneezing. And then he did it again!
I am a terrible mother, because watching my son half drown himself in the name of completing his tantie was the funniest thing I've seen in months.