So yesterday, I was setting off from a stop. My chain wasn't fully engaged on the lower sprocket, and so it slipped off with most of my weight bearing down on the pedal. I lunged forward unexpectedly, falling off my seat, and landing with the top tube in my crotch.

Luckily, I missed any soft tissue, however it freaked my out a bit. So is it prudent to wear a cup to protect your testicles? What precautions should I take to be safe?

thanks!