Sometimes, when you really want something, you might resort to whining and blubbering to get it — in other words, you'll snivel. It's never pretty, so try to keep your dignity, and don't snivel!
If you want a real picture of the verb snivel, consider that the meaning of the assumed Old English word snyflan meant "to run at the nose, to sniffle." Even worse, that was derived from snofl, or "mucus." Pretty picture, eh? The word came to mean "be tearful," and it suggested someone who was weak or nasty. Today it is often used in its adjective form, sniveling, followed by a contemptuous noun like "coward."