To pull down the wider part of somebody's tie to create a stiff knot at the top which is almost impossible to undo. Most commonly used as a prank in British schools where ties (long narrow piece of fabric tied worn around the neck and tied with a loose-ish knot) are usually part of the uniform.
Random Student: Got tiejacked 5 times today. Now I can't get my tie off.
A highly retarded instant message robot who thinks he is smart (hence the name SmarterChild) but is probably the dumbest, albeit funniest, thing in the history of the internet. Also a great way to waste time.
Luna: whats your take on jesus?
SmarterChild: What do you think my take on jesus is?
Luna: i think he should go fuck himself.
SmarterChild: Oh yes? Maybe you're right, he should go fuck himself.