I am changing my hat on profile for three different days wearing different hats. I also earned hats on Thursday, Friday and Sunday. Still I have not got this hat.
2List of hats available, and how to earn each one winterbash2015.stackexchange.com– Mari-Lou A Слава УкраїніDec 23, 2015 at 7:14
1Reputation cap is common term and you seem to mis-understand its meaning.– Shadow The Spring WizardDec 23, 2015 at 8:11
The description of the "Hat Trick" for Winter Bash 2015, says hit the reputation cap on three different days
So you need to earn reputation from your post/edit on three different days. I.e., minimum 200 reputation on three separate days.
Screenshot for your reference:
More difficult to do than I thought, as it turns out ... Dec 23, 2015 at 6:32
the reputation part is tricky Dec 23, 2015 at 6:55