WTF is wrong here???

I am a pretty laid back person. I deal with my kids craziness and my husbands lack of discipline in the family.
When my kids were little, it was cute for them to go outside in their diapers and play or naked in the little pool in the backyard. Our house was know affectionately as the "naked baby house" by Miss mania's friends.
But, now that they are getting older and know better, they think it's funny to go outside in their underwear.
Today, they were playing outside, on the trampoline, with the hose. Yes, they were soaked. I told them to come in and eat dinner. They come in, eat, change and go back outside. Hubby and I are sitting out back chatting when we see them come out with a shirt and underwear, towards the front yard.
Our backyard is secluded from the street so if they come out there inappropriately dressed, no big deal. It's when they get the bright idea of riding bikes, in the street, with a shirt and underwear. WTF?? I told them to come in and get some shorts on, but NO they proceeded to ride around in underwear, laughing hysterically riding around.
Where did I go wrong people??? Why do my kids torment me? It's anyone's guess.