how do you talk a 3 year old out of coping a squat on your front yard?

seriously - this story does NOT have an "April's Fools" ending...

this afternoon i was cleaning up the garage while t-man and little miss k were playing in the front yard and biking around our driveway. at one point, t-man quietly disappeared. i looked around for him, checked out the back yard, etc. and all i could find was his bike parked on our front walkway. i asked little miss k if t-man had gone inside to use the potty and she said something i couldn't understand - she obviously didn't know what she was talking about. so i quickly popped into the house and checked the 1st floor bathroom and discovered t-man busying reading a book while he was dropping a few kids off at the pool. i then returned outside to find little miss k hanging out in the mulch between a tree and a rhododendron off to the side in our front yard. i ask what she is up to and she says something again that i can't understand. i don't think anything of it until i do a double take, see her bare cheeks flash the cars driving by on our street since she has pulled her skirt and big girl pants down, and realize that she is telling me that girls can go potty outside too. i try to explain that t-man is inside using the potty and we're not hiking in the woods* - this is our front yard and there is a potty 20 feet away that she can use. she of course says "no - girls can go potty outside too." and the truth is - she's right. we let her pee all the time outside when we're hiking. so i decide to switch tactics - i then tell her that her pee will kill the grass and the flowers so if she really wants to go outside she needs to go in the backyard. i don't know what happened or what worked but she somehow ended up pulling her skirt back up and not going potty anywhere outside or inside?!?!? go figure...

* (and i'm thinking: "we're not tailgating next to the bushes in the outfield of ND's baseball stadium either")