Same with my little brothers; you will eat your vegetables come hell of high water, but i'll keep good on the chocolate icecream for afters.
Also the only one who'll (much to the horror of my step mum) pick them up by the ankles and pretend to mop the floor with them. Or grab any two limbs and spin them around until I can't walk straight.
Random sillyness is what builds the best childhood memories. You're never too old to build forts, make mud pies, and slay dragons.