Oh golly, this brings back memories.

Indeed it does.

I am sorry if it is insulting, but... ^{... I don't get it.}

It is simple wordplay.
sarchasm = sarcasm

Ah.... But what does it have to do with old memories?

A long time ago--I believe before I came on to this forum--a chasm not unlike that one was used frequently to denote internet sarcasm.

Were you in a galaxy far, far away?

No. I don't remember which version of NP it was. I think it was 4, but people who keep track of this stuff usually give me the correct number when I say "I remember a rubix cube with chess pieces on it."
As far as I know, the Sar Chasm came from back in the first or second version.