When our kids were younger my wife captained the tandem with our daughter stoking, while I piloted the triplet with our two sons working the child stoker cranks to the max. FIVE chains.......don't even ask.
At those young ages they were really into it, and whether the comment was "Hey, they're not pedaling" or " How come they're doing all the work" we always responded by me unclipping and holding my feet out high, wide, and forward as they got out of the saddle and kicked a$$.
My favorite comment heard only once by a guy that must have actually been capable of decent comedy was "Whoa,..... squirrel power!"