look up any word, like eight ball:
 
1.
Usually a dude who likes to hit on guys and being really shady at night and often hitching a ride from strangers that end up in some dangerous places.
"Man, he was such a sithu last night"
by tupperware431 April 24, 2008
 
2.
A common burmese name that is often used because it is easy to remember and call upon expecially for a boy.
Maung Sithu or Sithu "burmese name" or "name" Sithu
by Sithu November 04, 2005