Yeah, I'm a native English speaker, but this a highly linguistic question concerning semantics.
I was just listening to a song with the line 'Baby, you are killing me'. Now, obviously in this circumstance 'kill' does not mean 'to end a life' or 'to cause to no longer be alive'. Its something more abstract. I'd like a way to define this usage.
'To kill' in English can often be used to refer to more than just 'ending life'. For example, it can also mean 'to turn off completely', such as in the phrase 'Kill the engine'. Interestingly enough, in this usage it's ditransitive: "He killed the engine" versus "The engine killed". Both relay the fact that the engine was turned off completely.
It can also refer to bringing an end to things. Such as in the noun 'killjoy'. This refers to someone who brings an end to fun. For example, if some teens are having a rowdy party and a cop comes to bring an end to it, he would be referred to as a 'killjoy' by those teens. The word 'buzz-kill' also has similar connotations, though in this case it refers to someone who's boring or dour, and tends to ruin the fun for everyone else inadvertently.
Though oddly enough, the word can also mean to be highly successful in some circumstances. For example, the phrase 'to make a killing' means 'to be making a lot of money, typically with ease'. It can also be used with comedy. The phrase 'This one's a killer' actually means 'This one is a really good joke'. Also, to tell a comedian he's 'killing the audience' would mean he's doing a very very good job of making them laugh. The Joker of DC comics often draws on this theme of 'killing' being related to 'jokes', since he's a highly sadistic prankster and a murderer.
This also brings me to the meaning I'm looking to define. One of the most famous comics featuring the Joker is 'The Killing Joke', which tells of his fall into madness. In this case, obviously 'killing' is a poetic way of referring to the end of himself as a normal and sane person, and his becoming the infamous madman known as 'The Joker'.
Also, a few weeks ago in my astronomy class, my professor said the phrase 'You're killing me' to one of the students. In that case, we were supposed to be doing an activity but one of the students was more interested in goofing around with the various toys he had scattered around the room (as for why a college professor would have children's toys in his classroom, I don't know, supposedly he uses them for physics demonstrations). I understand what he meant when he said that, but I don't know how to define it. Annoyance? Disappointment? Irritation? I don't think any of those are a good match, but I feel 'irritation' is on the right track.