I remember joking to friends once that this was on my bucket list after taking a ride on the back of motorcycle in a bikini. Honestly I think it would be possible given time and the amount of vibration. Wrap your arms around a hunky guy, a bit of pressure, grinding, against what is in a sense a giant vibrator. I can get myself close just by crossing my legs and contracting my muscles. I've read there are women who orgasm hands/toy free by using this method, some just have to concentrate (I saw a documentary were this was scientifically monitored and done hands free). Although I've never been able to push myself over the edge without a little touching. But if you throw in the vibration, which would be key for me, from the bike I think it's certainly possible.
As I stated, bucket list baby. :tongue: