"Accidently" spill this on their jacket or shirt.
They head right to the bathroom to wash out the "stain".
It will disappear and they will think they were successful.
Meanwhile, you got them away from where you didn't want them to be or isolated them right where you wanted them.
The limits on this as far as practical jokes is also as endless as your imagination.
The disappearing ink magically vanishes within minutes.
Each squeezable tube contains one ounce.
You get 2 tubes!