1) Noun. A relatively insignificant event in life that people can't help smiling about
2) Verb. When someone does something/executes a plan to cause a relatively insignificant event that people can't help smiling about to happen. A small gesture that makes someones smile.
A: I would've been late for my meeting if a total stranger hadn't held the lift for me!
B: No way! That's such a JLT :)
A: My daughter took her first step today!
B: Awww what a JLT!
A: What did you end up doing for Becky's birthday?
B: We handmade a scrapbook and a mixtape with her favourite old songs.
A: How sweeet! :) you totally JLT'd her.
B: Jess I'm so stressed with this wedding!
A: Chill out, I found the PERFECT dress for the big day :) you just got JLT'd!
B: Aww Jess you shouldn't have!