I have a colleague who is allowed to work from home some days and is taking the piss. He openly told me that he doesn't work the whole day and loves working from home to spend time in the garden and do things in the house.
I'll admit I'm jealous as I'm not allowed to work from home (my manager doesn't like us to) so I have to commute and then sit in a hot and stuffy office with no air con. My job could easily be done from home.
Colleague often sends me and some other colleagues lots of messages and pics during the day while working from home, of pets or memes etc. I've told him I will not be responding to any messages sent while he works from home as he should be working and not sending such things if he gets the privilege to work at home. He has called me petty (I suppose I am a bit).