I was dating a guy who shared an apartment with 3 other guys and 2 bedrooms. Two guys in each room, but at least the rooms were spacious and clean. Sometimes I'd spend the night and the two of us would sleep spooned up together on his twin bed. His roommate, Tom, was a pretty heavy sleeper and didn't care if I stayed over.
One morning we woke up and cuddled as the sun was rising, we could hear Tom snoozing away. Cuddling turned into kissing and kissing turned into heavy petting. We were both very turned on, headed right for the big O and trying our best to not wake Tom.
Just as we both reached that pinnacle moment, Tom's obnoxiously loud alarm went off, "BEEP BEEP BEEP BEEP BEEP BEEP BEEP BEEP BE- SMACK!" and Tom woke up and slapped the snooze button for a few more minutes of sleep.
I felt oddly frozen, like a cartoon character being electrocuted - the great enjoyment of the moment couldn't be stopped, we were both stunned by the alarm but couldn't control our bodies, and we had to squash our sighs of relief and be still when Tom hit the snooze. We laid there silently to collect ourselves for a few minutes, then casually went off to the bathroom, suppressing our laughter.
It became our little joke about "Oh, ahh, ohhh, BEEP BEEP BEEP BEEP BEEP BEEP" and how hard we laughed afterward the bathroom.