While I'm tempted to stop, swing my bike perpendicular to them blocking the lane and pretend you have to tie laces, tighten velcro on the shoes. but here in the wilds of the Bay Area I don't wanna start trouble.

A subtle nod of the head towards the other side of the road is about it. Even that if they are truly newbies may make them swerve into me or worse. So I just watch it.