Try fooling arround with Sin&Cos, then use some script to setfocus a part of the destination where the next mark would be, and leave it run around wild.
Using setfocus, of course...
Erm... Wrong question answered. Make the topic more on topic: use
TIMEOUT, and
drunklevel --. I think that's it... Wavy Vision is expressed in first answer, decreasing of drunk level in other.