Not sure why is this sentence shown in the current discussion, but let's point out that it would be normally understood as waiting for someone stupid, not waiting for an actual animal. Probably the same as in English.
Huh. I'm a native (US) English speaker, and it would never have crossed my mind to interpret this sentence as waiting for someone stupid. I've NEVER heard the word "donkey" used with that meaning. "Ass," on the other hand, certainly is... and for a bit more than just "stupid"! :-)
But those are two different words. Does Czech use "osel" in both meanings?
Yes i believe in Czech language that osel/donkey means also stupid. The same in Polish. We got a lot of animals which feature some behaviours. Osel (osioł in Polish) is one of them and means someone stupid.