It might not be their fault!
It might not be their fault directly, that is.
Ever noticed an unusually high correlation between those people with tongue piercings and those people with peculiarly uncoordinated physical motions? Turns out there might a causation link:
Cerebellar brain abscess associated with tongue piercing.
The abstract claims that "[the evidence] suggests that infection of the tongue piercing site was the source of the cerebellar abscess". So if you've ever wondered whether there might be something amiss upstairs in those that decide to insert a metal bar through their primary taste organ, now you have some medical research to back you up.
Incidentally, I've never noticed the correlation I proposed at the top of this post. In fact I've never consciously questioned the cerebellar integrity of those with tongue piercings specifically because of the tongue piercing. Truth be told, I actually think a female tongue piercing can be kind of hot. I just thought it would be a nicely controversial piece of rhetoric to divide the audience.