LMGTFY is just a tool -- it can be used in good humor or malice. This site, likewise, but it has the added benefit of promoting DuckDuckGo and producing brand exposure, and is therefore less likely to be taken as a slight; with LMGTFY, everyone knows what Google is, so they don't take that as an informative thing; with LMDDGTFY, few people know what DDG is, so they may just assume that the linker is humorously and conveniently promoting a new search engine out of personal preference.