This comes from an episode of "The Simpsons" in which the geeky and unpopular character Milhouse enjoys a small number of fortunate happenings, such as finding Ten Dollars. In response to the lucky occurrence, he exclaims "Everything's coming up Milhouse!" The total expression is reduced to "Millhouse" for convenience. Millhouse is a misspelling of Milhouse.
Person 2: "Shit Home Boy - that sure is some disgustin' stuff goin' down - he oughta be ashamed of his skinny white-ass"
Person 1: "fo-shizzle - he one sick mutha - you just gotta feel for that Rodent"
Person 2: "Word... take a look at his face tho - he in real deep homey.."