I'll let Freya show you on Tuesday
Or ask Lorna: she held a workshop on it recently
...
It's when the follower stops following your lead and does something completley un-led or trys to lead you for a bit. During this time, the lead has to be ready to pick up the threads of the dance when the follower has 'finished'.
look at these threads for more stuff:
Ladies' sabotage advice Sabotage moves