Unfortunately the only aunt-uncle combo is based in NZ, so it'd be more than an afternoon...

AFAIR playgrounds are good. Choose one with a convenient bench from which to watch. Or join in if you're not self conscious. Something requiring concentration, like Lego can be surprisingly tiring. The best thing is to forget your boring adult lifestyle and simply play all day.

[penelope] I looked everywhere but found no trace of these canine-oriented ball-atlatls you steered rab toward. How would the dog wield such a thing anyway, absent opposable thumbs? What rab needs is a keen, ankle-nipping bull terrier. Half an hour of being chased around the park by the dog will tire the child out nicely, and give him or her a healthy respect for vicious dogs.

Of course, if the dog is too keen there is a chance the plan will backfire as the dog chases you instead of the child.

To help prevent this possibility, soak the child's shoes in bacon grease before releasing the terrier.

Also, to minimize the risk of vigorous shoe-licking instead of ankle-nipping, thrash the dog soundly for five minutes a day with a side of bacon.

This sort of preparation escalation is why children should be avoided in the first place, of course.

[Stevie] We have managed to do that. We are, however, expert in Unclage and Auntage, with the proviso that the assorted nephews, nieces, godchildren and fledged apprentices repay us by taking us for interesting outings when we are elderly.