More than silly or off-putting, I found it confusing. Maybe some form of clicks and rubs that sound more like drawing and cocking a gun like the opponent is cheating and getting ready to shoot before the signal? Or some... old western sounds like horses neighing or wagon wheels squeaks? Rooster crowing? Church bell ringing? Gun firing in the distance? Anything that doesn't break suspension of disbelief rather than going for silly, I'd suggest.