I must admit that with the right audience I do say 'groovy' or 'far out' a couple of times a year.
"Cool" seem perennial; I like that!
I hate when people put LOL in so many posts, but it is the equivalent to 'Ha-Ha' in old people's writing that drives me nuts, too. At least I am consistent!
Most other things that annoy me will eventually go away. For example, I haven't heard something like, "I like that -- NOT!" or some sort of "EEEP" for an unacceptable response for a long time. I guess "I'm good" instead of 'No thank you" is acceptable and makes sense, and "No problem" instead of "You are welcome" makes sense, too, so I can live with them.