I've never heard of a yipper-snapper, but I have heard of whippersnapper, which is "a young and inexperienced person considered to be presumptuous or overconfident." Hope that helps!

The expression is "whipper-snapper", and it's an expression used by older people to refer to younger people (usually in a slightly derogatory way).

Yipper Snappers are delicious gourmet dog treats. My dogs love them!! Pick them up at yippersnappers.com

Oh right and it's whipper snapper...not yipper haha.

As others have said it is a young and experienced person. Generally used by somebody older to somewhat jokingly refer to a younger kid. Generally used between an older man and a younger boy (Like a grandfather to a grandson). The closest Chinese equivalent would be something like "小伙子".