—used to express joy, approval, or excited enthusiasm
NASA's social networking presence took off with the Mars Phoenix Lander, which tweeted, "Are you ready to celebrate? Well, get ready: We have ICE!!!!! Yes, ICE, WATER ICE on Mars! w00t!!! Best day ever!!" on June 19, 2008.—Amanda Stratford, Florida Today (Brevard County, Florida), 16 Oct. 2008
—often repeated
I know of some organizations whose events exceed their budgeted goal (woot woot!) and others who hope to break even and must decide if it's worth repeating.—Alyce Lee Stansbury, Tallahassee Democrat, 6 Apr. 2014
Word History
Etymology
perhaps extension of whoo entry 1, with t representing glottal closure