Watching a child across the road learning to ride a bike: She's been riding up and down the stretch of pavement for a while now, and the (single?) bolt attaching the port stabiliser appears to have loosened, to the effect that it pivots up out of the way whenever she leans to that side. After a series of unplanned dismounts she's successfully modified her starting-off strategy to compensate (leaning to the right to maintain tricycle steering dynamics), and seems to be in bicycle mode once she gets some speed up, so with any luck she'll have cracked it by the time the starboard one comes off...
ETA: Her mum's gone and spoiled it by callingyelling them into the house.