Dropbox and Cactuses or Cacti?

I really like Dropbox and their fantastic sync service - a serious and valuable software, highly reliable, stable and efficient.

Once in a while I even read some of their forum discussions - you get quick responses and no-nonsense discussions.

But today they (aahm - some users) talked about Caci or Cactuses. Yes - the plants with spikes or stings. Made me laugh...