The Serbians made a poster saying "Sorry, we didn't know it was invisible" after they shot down a stealth F-117. The full story and a picture of the poster at this link: https://www.warhistoryonline.com/instant-articles/serbs-shot...

> During the 1999 yugoslavia bombings, after the first one was shot down

That was a F-117 Night Hawk “Stealth Fighter” (a type which is now retired), not a B-2 Spirit “Stealth Bomber”.

Incidentally, the F-117's fighter designation was a misnomer; they were only armed with bombs.

Not just the “F” (“A” would be expected from role), also the “117” was anomalous (under the standard numbering convention, it should have been something like the 19 if it was in the F series, which is the designation that speculation about it was typically associated with before it was officially announced.)