Along with hearing someone walk in the door, or thinking you did (see "False Alarm"), the California Drop is a leading cause of prematurely ended porn watching sessions, sometimes resulting to frantic, E.R.-like attempts to resuscitate one's erection.
During these times, it is admissible to either:
A) Get up and wash hands, thereby terminating the session in defeat
B)Fast forward, or rewind, to missionary position
"Hey, this is a pretty darn good porn video"
*Camera angle switches*
*Rewinds to missionary position*