If someone says such a word to you, you can be pleased!
Because it means,
“You are cool”
“You are attractive.”
“Iketeru（イケてる：いてける）” began to be used by comedians in a TV program around the 1990s, and the viewers started using it as well. Now not only young people but many adults use it, as those comedians are now adults, too.
There are various opinions about the origin of this word.
Let’s take a closer look at “Iketeru”.
What does “Iketeru” mean?
“Iketeru（いけてる：イケてる）” is used to mean cool, attractive, stylish, interesting, good, or anything that you are pleased with. want to anyway. You can use it to express anything, such as a person, an object, a state or a situation.
The opposite word of “iketeru” is “ikete-nai（イケてない：いけてない）”, not “ike-nai（いけない）”.
People who are studying Japanese may be confused with “ikete nai”.
The TV program which created the word “iketeru” is called “Mecha mecha Iketeru (aka: Mecha Ike:めちゃ2イケてるッ! -What A COOL we are!-)”.
This program was the long-run, started in the 90s and lasted until 2018.
They kept saying “iketeru” to express also some sort of mixed feeling of “you are doing fine”, “you are funny” or “don’t worry about it” in addition to the meanings mentioned above.
And they started to say “ikete nai” when showing the opposite meaning of “iketeru”.
I was watching the program in the 90s and felt a little uncomfortable with the word “iketeru”. Furthermore, an additional word “ikete nai” came out and I felt double discomfort.
Over 20 years since then, “iketeru” and “ikete nai” are now used nationwide anyway. Even so, the word is slang after all, so it’s mostly used in casual situations.
It is said that the origin of this word comes from a slang “Ikasu（イカす：いかす）”, “ikeru（いける）” or “ikeike（イケイケ：いけいけ）”.
Also, the slang “ikemen（イケメン）” has “ike” from “iketeru” in it.
“Men” of “ikemen” means “men (めん：面：face）and “a man”.
So, “ikemen” means “a cool man” or “a handsome man.”