I think some of the rare item challenges might need tweaking. I get that they're supposed to be more challenging but this one I just got; 5000 nothings in an hour.... seems kind of impossible.

On Classic monkey I had fed, all but the last tier completed on (aka about 1150 hammers) + 2 bananas ready to go, around 30ish stars, a dozen or so hammers, stars, etc saved up, around 1500 bronze tokens for purchasing hammers/stars, whacking on the bronze tier, even switching back to the default hammer so I have no higher chances of stuff other than nothings; using all that I only made it to 602 Nothings with 17 minutes leftover.

Even assuming I had 40 hammer sacks saved up instead (which is quite a lot), I probably would've only obtained another 50-80 nothings. Now I did use MB tokens, but again even assuming I had gone piece by piece and avoided gold eggs or buffs, there's no way that would've added up to even a third of my total. So theoretically, the absolute best one could realistically hope to get is around 800-900 nothings.

Unless it was a programming typo and was supposed to read 500 nothings...

Multiplying nothings does count and using multipliers is the best way to beat the challenge.