I set aside money to buy a brand SUV when I retired, but it was not intended to be a treat - - this was part of my financial planning, to protect me in the event of a bad sequence of returns after retiring. I just didn't want to have to come up with the money to buy a new car unexpectedly so I saved the money that I would have spent for it previously, and put it aside for that purpose, outside my portfolio. I bought it about 2 months after I retired.
As a treat for myself, just a day or two after retiring I bought 3 pairs of long black pants like I used to wear all the time at work. Dumb idea!!! I don't wear that kind of clothes any more at all. I didn't realize that I would wear different clothes in retirement than when working. But it was fun at the time.