This is one we plan to do as a charity drive. We want to get some corporate sponsors to pay a rate per pullup. They'd sponsor an individual say R2/pullup, and hopefully raise say R2000 for the nominated charity.
Guys are aiming for 1000 reps, girls for 500.
We've done a "how many pullups can you do in 1 hour?" and the best score there was 363. There's a dramatic slowing down after the first 30 mins, so I expect this would take about 4-5 hours to complete. Probably a week of recovery from the stiffness too, but hey, that's how we learn and get stronger!