etymologically, i think it means "the science of annoying" or such. I didn't know that this word exists! Anyway I agree with XiangAbe

haha i didn't know this word exist, i only heard this word now anyways.. I agree to XiangAbe's answer ^^

It is just a word twist. Friends use it to joke to each other. It means the art or science of pestering or annoying someone. It is a taglish word "combination of Tagalog and English". Buwisit means someone who is a menace or pest and ology is the english suffix of the study of one science. So some friends will joke to each other to show the other that he is becoming a little bit annoying by saying " aha, siguro nag masters ka ng buwisitology at magaling kang mang asar" translating, "perhaps you mastered in the study of pestering that is why you are real good in vexing". Sometimes, the phrase is also being used in sarcasm depending on the situation and the facial expressions at how it is delivered. So, by raising this question, I applied some of the my buwisitology (Joke!!!, hope you don't mind)

just heard of it now too ^_^, I think its from the word buwisit.

does it really exists? hehehe. :)