Early in our Sex life we had a similar eperience to the water-glass-on-the-head-board situation. Only instead of water it was a candle on the bed stead......ouch!
We ended up with hot wax all over his chest and my thighs! (<~~~Cowgirl)
I know.... I know... you thinking "Hot wax? kinky!", but in the dark and unexpected, it was painful and ruined the moment.
.....................At least we can laugh about it now.