Well I guess it would depend on what else changed that day? If it were only my dick replaced with a vagina... I think I would freak out!
Assuming I swapped my body for a girls for the day, I'd dress as sexy as I knew how, get my hair and nails done and go out on the town! Think it would take more than a few days of getting used to it before I'd like a guy down there... but I'd enjoy the stares for a day and then go home with the large dildo I bought while I was out (teasing the guy behind the counter where I bought it) and play until I changed back.