First explenation:
Bosnia didn`t exist as a country before, until comunists made it. It`s HUH LAND because coutries usualy have people of a certain nationality, but Bosnians never existed as a nationality in the past. They were artificialy made overnight so everyone is wondering "What the ... is a coutry called Bosnia?".
Second explenation:
We in Serbia have a lot of jokes about Bosnians being stupid, so that may also be the reason.
I`m not sure which one is it, but I suppose it`s the second one.