Have ever done this. I know this might be personal matter for some but some might have fun stories.
Here’s mine I had a crush on girl which was in school with but not in touch for sometime. And I didn’t have the guts to say straight so I said good things about her on ask.FM as anonymous and even told her about my crush she said come off.
And I PMed her on IG and she blocked me from her IG but that was just a hurried decision I had to apologize to her and now she says it OK. LOL