Dattebayo

What does that mean?

~tteba is the contraction of ~to ieba ("if I say so"), which is commonly used when you're repeating something you've said already, and want to sound a little irritated.

え〜、ラブレター？
ちがう。
やっぱりユコちゃんモテるんじゃない。
いや、だからっ。
あっ、ユコちゃん真っ赤だ。かわいー。
ちがうってば！人の話を聞けよ！

So '~tteba yo' should mean pretty much the same thing, except it's not very logical, and it's not used in real-life (Narutards aside). It doesn't sound macho at all to me, though. ~tteba is more common woman or child speech, I think.

By the way, 'de masu' doesn't look like a reasonable gobi to me. Perhaps you meant 'dearimasu'?