I love how reliably abbreviating "something" (e.g. "sth", "smth" or "sthg") indicates that the person isn't from an English-speaking country. I wonder why this abbreviation has never caught on in English-speaking countries. I think the abbreviations got popularised in non-English-speaking countries by English dictionaries.
I think the more common idiomatic "abbreviation" would be "do_stuff" when you don't want to type out or say "something".