I came across this word (ぶえっくしょ) recently and tried looking it up on every site I knew. I assume it's slang. The line in which I first saw it is:
「あいつだって、いつも読んでないわけじゃ………ぶえっくしょ!!」.
As I was researching it, I saw it in two other forms:ぶえっくしょん and ぶえっくしょい (sometimes ぶえっくしょーん or ぶえっくしょーい). Does anyone know what this means and what it is? Also, does it belong to a certain dialect?