It is a ONESIE not an ONSIE. You know, the little one piece shirt for babies with the buttons at the crotch? Its ONE piece which makes it ONESIE. Not something ON the baby to make it an ONSIE. 

LMAO 

It's actually more likely an infant body suit. Onesie is a registered brand that is often used generically much like Kleenex.
The more you know. 

I just hate when people spell it wrong trying to sell them, Its like when they say they have a "Dresser for sell, with 6 draws" Hukt on fonix wurkt fur meh. 

Or a chester of drawers... 

I once sold a "Window AC unit" as a "Widow AC Unit" it sold fast and got some laughs. But that was a typo, not stupid spelling.