I assume the expression is derived from "baby's first ...". I have seen the expression used mainly for online discussions of 'geeky' or 'nerdy' stuff. A quick google search gives me: babbies first linux, babbies first wallhack.
The usage of the expression seems to be intentional (e.g. not due to a type). The gentoo wiki -- which has good reputation -- has a 'babbies first linux' page.