Please help me about this word

[Gun[Lengend]]

I don't know what is mean : Boof
Can you tell me what is vietnamese mean ? Or u can explain it with English to express to me ?
I have a picture :

In the top of page, the character express her angry ( so like that ^^! )
The sfx : boof => what is mean ?
And this word : だ so like the word in the picture. But is mean " I ", it not logical. Can some one help me ? Plzz !

[dewdrops]

http://www.urbandictionary.com/define.php?term=boof

I only know it as Jeez you've got boofy hair..hair that is all over the place..etc..didn't realise there are many more definitions..lol..

[Tricky42]

Here, the word Boof comes after SFX: which a system for generating sounds. In English 'boof' sometimes signifies a striking sound but not a harsh sound. Therefore, I think the SFX: Boof text means a 'boof' sound.

[AlienUFO]

Ya like when you pop a balloon that will sound "boof" also.

[Gun[Lengend]]

Thank for all opinion.
But i'm Vietnamese. Someone can talking with me by Vietnamese. ?
Thank All

[vietnamese4u]

if it's a sound then it must be like "bụp" in vietnamese

[Gun[Lengend]]

thank for you help.