if you'r a bloke , have a crafty w*nk under the desk whilst looking at the secretary
If you'r the secetary, look seductive and try and work out who's having a w*nk
If you have a phone on your desk you could play th dave game. Just ring a random number and ask for dave. If theres a Dave there your a winner!!!!! You can also take it international by asking for a name that is th equivalent of Dave in that country! E.G. Vladameer is the Russian Equivalent! Its always fun! Or just phone different extentions in your office and prank them instead always a luagh!