Also used in offices
(which, let's face it are just glorified playgrounds
in many cases).
This is probably based on its renaissance, courtesey of Rob Newman and David Baddiel, and the other two who weren't as funny (Steve Dennis and Hugh Punt, or was it Steve Punt and Hugh Dennis) off TV's The Mary Whitehouse Experience, who used the variation:
Accompanied by the aforementioned furious rubbing of the lower chin, of course.
And let's not forget the all important pronunciation of reckon as "reck-on", rather than "reckun."