OMG Tigger!!!
I've done the SAME thing!
I was at an event in one of those big fairgrounds buildings and they had bathrooms with no doors, just a wall. You walk around the wall and you're inside. To the left it's the ladies' room and to the right is the men's room. Well, I didn't see the sign and went to the left! Somehow, maybe because it was early and the coffee hadn't kicked in yet, I never noticed the lack of urinals and went in the stall and sat down. Just like you, I heard female voices and the cold, embarassing reality set in. I finished my "business" and when I didn't hear anybody, I pulled my pants up, threw open the stall door and made a run for it! I sprinted out of there like that Jamacian fellow that won the Olympics. I don't think anybody noticed
