Obviously people who report their pushups in that thread are lying. The price chart clearly shows that they are doing barely 68 pushups instead of a hundred.
I just did 3 pushups (my personal record) so expect the price start trending towards 3k. You're welcome (for the chance to buy cheap bitcoins).
Who's to say if they are lying or not? As long as there isn't proof, you'd just have to agree that they do it. AFAIK, you can't jinx something when there are other factors affecting it. That's just superstition and that thread was opened so that more people can be encouraged to hold and also exercise to keep fit.