Seriously. That's what it says. In all honesty, I think it's supposed to be more of a "poing" sort of sound with a drawn out "O" sound because the character is jumping, but... "pooing?" That can only be taken as something else. I mean, come on. It'll be a fun challenge to try to not make it look like it actually says "pooing" and make it looks more like a jumping sound.
I think this shows my mental maturity though... I was laughing so hard I thought I might wet myself.
I wanted to participate in "Blog Like it Isn't You" day yesterday, but I got caught up in work and Fanime prep stuff. Bah. =\