For some reason I'm bothered by you saying 'get it' and linking to urbandictionary. To me it implies some kind of slang word or internet term. So I'll link a more normal dictionary or two.
The urban dictionary entry is the first one using YHWH in the link title in my google results. It's the third result total, but the first two use 'Yahweh' in the link title, not YHWH
http://www.thefreedictionary.com/YHWH http://dictionary.merriam-webster.com/dictionary/yhwh