I don't mind the brags on social media, but I can't stand competitive parents that do a double whammy brag but put your child down simultaneously.
Years ago when my youngest child was a baby I met up with a woman a few times, from a meet a mum type online forum, who had a baby a week older than DS.
She was probably the rudest, most competitive parent I've ever come across. Literally every time she opened her mouth there was a sting in the tail about my DS, or about my older DCs. Everything they did was apparently so much better/cleverer/more advanced/more classy than anything my kids did.
There are so many examples of things she said, and they were all tiny things but they just all added up together to make a load of competitive poison really. I remember once she asked me about a drama club my eldest child attended and I said they were doing a performance of a certain play and she did a really nasty laugh and said 'Oh the drama club my older DCs go to would never perform that play, but then their club is so expensive '
Also nasty comments about baby DS, said passive aggressively to him 'Oooh does mummy not like you today, making you wear those trousers?' and 'Oooh goodness me, look at you with a biscuit, little Daniel (her kid, not his real name obvs) is wondering what on earth you're eating as he only likes his organic vegetables as snacks'
Vile bitch!