Adventures in Dungeons and Dragons with kids

So I play dungeons and dragons with the kids and they love it. They are a bit too young and I have streamlined the game to make it age appropriate. Drake is 4, Zoe is 7 and Gryphon is 9. They are all into fantasy and this makes them be creative and interactive instead of having their faces in video games 24/7. I have personally played for three quarters of my life. The other night I had a first.... and hopefully a last. I got mooned. I'm not talking about the periodic 1/4 crescent moon you might encounter when a chubby gamer drops his 4 sided die and dips down for it before you have a chance to completely avert your eyes. We're talking a full moon. I'm completely in character and describing the palace of a powerful Genie and speaking for him in a booming magical voice. I look up and Zoe is listening to me intently. Gryphon is listening to me intently. Behind them is a surreal pair of legs without a body like something out of a Dali painting. I have no idea what it is yet as my brain processes the information. It is Drake. He is turned around backwards and bent over so far you can't see his torso. His hands are gripping his cheeks. "Oh my God!! What the Hell!!!" my brain registers.... but it was too late... The brown eye of Mordor had fixed it's gaze upon me. The other kids turn to look. "Drake what the hell? What the hell are you doing? WHY!?!?!" Drake, "I don't know". Zoe laughs, Gryphon laughs, I can't help it. I don't want to encourage this sort of behavior... Drake laughs. Damn it, I laugh... "Well pull up your damn pants and don't do that EVER again."