To lose an erection and thereby become flacid.
"Last night, I was about to finally bone my girlfriend. But then I dropped my sword, and she said the was no way." - Canadian guy from Family Guy
"Yo Tyro, I heard that Megadam dropped his sword in bed with yo mamma last night." - Random American/Irishman
"Drop your sword again, Adam, and we're through" - Katrina