The punishable line on offensive behaviour

Recently I've been getting a few popups saying I've been reported for "offensive language" while jungling, this is usually after an evening on gaming with friends, most of the time I've not talked in chat as I've been on, however, in some games, I've counterjungled while ahead and said something like "that's a nice blue buff you have there Amumu, it would be a shame if something were to happen to it" while he's ganking the other end of the map and I'm safe. Once or twice I've told my team to run like a Kenyan as their nation is famed for their atheletes, now the question is, am I being reported for saying "nice blue buff, shame if something were to happen" and some other, that level banter (another example: last game I killed the enemy jungler in his jungle I said "hi Yi", then killed him again and said "Hi Yi :D" then he killed me in mine and said "Hi Graves")

Am I being reported by sore losers on the other team, people who take the banter badly, or am I getting warnings because I rarely if ever get reported and "run like a Kenyan" is offensive to a few.

The games I get the warning screens on are usually games where I've not said anything, save the odd "gj" when a gank went well, or a "damn nearly got him" when the enemy escapes the gank.

I'd also like to know what counts as "the line" I've been in games where I've been called all names under the sun, and I've been in games where I've told someone to stop being a dick to someone else.