If you get on your friend's shoulders, put on a trench coat, and try to buy one movie ticket, they'll obviously know what you're up to. You see, your weight would make your friend wobble as he walks. And since you still have a child's face, they'll know you're not an adult.
Instead, you would need to build a special frame that would hold you up, taking [music] the weight off your friend's shoulders. And a rigid pole would connect you to a harness connected to his hips. Mechanical leg braces would help lift your weight, allowing him to walk straight.
And a hyperreal latex [music] mask would change your face, making you look old enough to match the height.