Try this -
Lie down on your bed - darkened room. Close your eyes. Put you right hand behind your head. Make sure that your arms are bare. Slowly and lightly trace along your tricep muscle - as lightly as possible, from elbow to underarm. Small circles under your underarm. Continue, as lightly as you possibly can, for 2 minutes. If available, try a feather or q-tip as well. I am primarily a 'ler, but this tickles me like crazy! Although, I have yet to make myself laugh spontaneiously from this, the tickling feeling drives me crazy.