I just wanted to put my thoughts down about this particular well-used phrase. In my opinion it's one of the stupidest things you can say to a teammate. At best it does nothing, at worst it can cause someone to start trolling, flaming or inting, none of which are good for your team. Consider this, if someone is dying a lot they are either trolling/inting or are just having a bad game. If someone is already inting then you saying "stop feeding" isn't going to make them magically stop, anymore than telling a serial killer to "stop killing" is going to make them stop.
If someone is legitimately trying to win but keeps dying, you saying "stop feeding" is more than likely going to tilt them. The irony is that you saying "stop feeding" is more likely to make them die more. Either way, it's not going to help you win. The same goes for spamming pings on someone.
I know it gets frustrating to see someone die so much but can we please think about what we're typing before we hit the ENTER key?