because altho we don't do it as a past time, sometimes it's inevitable that we have to take them (shoe shopping/ dh away and need food) and it seems that there is a limit on good behaviour, and when it runs out, they start hiding in clothes rails, wandering along following the floor patterns and crashing into people, playing chase etc etc which I find excrutiatingly embarassing (mine are all ds, age 2, 5 and 7)One to one they are fine and engaged, but they just can't walk along quietly...