Found on another forum....
Around here (California) the universal signal for cops or radar is a left hand flat palm tap on top of the helmetas well.
It's good for a group of new riders to decide what their universal hand signals are gonna be.
As a matter of fact, here's a quick list.
Cops/Radar/Speed trap ahead: Left hand flat palm tap on top of helmet two or three times in succession.
Turn signal indicator left on: Opening and closing a circle made with the thumb and forefinger of left hand.
Turn on high beams: Fist with left hand, then point index finger straight up, raise and lower finger without moving fist.
Turn off high beams: Fist with left hand, then point thumb down, raise and lower thumb without moving fist.
Increase speed: Left hand thumb up motion moving left hand and thumb in repetitive upward motion.
Decrease speed: Left hand thumb down motion moving left hand and thumb in repetitive downward motion.
Debris/Hazard ahead in road: Kick right foot slightly outward twice.
Tighten formation: Extend left arm out, with elbow bent and fingers pointing upward, then bring flat palm to side of helmet. (Slide arm into position from side of body to avoid signal being confused with universal hand signal for right turn.)
Loosen formation: Reverse of tighten formation. Start with left hand flat on side of helmet, move hand away from helmet.
Need fuel: Point to top of tank with left hand index finger, tap on the tank cap or cap cover.
Check out the hot babe: Left hand to chest as if cupping breast. Repeat cupping motion. Then point in direction of hot babe. [http://www.kawiforums.com/images/smilies/tongue.gif]
Begin show/stunt: Tap left fist on top of windscreen twice.
End show/stunt: Move left hand back and forth over top of windscreen in a wiping motion.