WIBNO is a phrase my mom coined: “warmly invited but not obligated.” English doesn’t have a succinct, clear handle to describe the sort of invitation that avoids placing obligation on the other person’s shoulders, but that also clearly signals that they’re actually welcome to join.

That’s pretty frustrating, and often leads to roundabout stuff like “no really, you should totally come, but, like, don’t feel pressured or anything. but we’d really love to have you! just don’t feel bad if you can’t make it.”

Some examples:

• my mom would use it when she and my dad would be doing something fun (e.g. going out for dinner), knew that I might like to join, but also knew that I might have meetings/work/other commitments — “hey, Dad and I are going out for dinner, you’re wibno”
• inviting someone to a community dinner that you’re attending — ”i’ll be going to Taco Tuesday tomorrow, wanna join? you’re wibno”

Related: I’ve seen Ricki use “max invite min pressure”