adj. Slovenly or unkempt, especially due to laziness or lack of self-esteem.
Other Forms
So, if you want to get ahead, ditch that Chanel trouser suit for jeans and a hoodie — looking like you’ve just woken up might just help you rise in the world. When in doubt, turn to those already pulling off schlumpadinka chic to perfection.
Clothes aren’t everything; and neither are looks. But, even if you don’t work or are at home all day long, there’s no need to spend your entire day in pajamas. Sure, we’re all entitled to those kinds of days, but, you should "get dressed" more often than not. Getting out of "schlumpadinka" mode will help you feel better about yourself — and others, even if it is your kids or spouse — will see your confidence shine through.
—Ashley Boynes-Shuck, “Self Esteem, Body Image, and Chronic Illness,” MDJunction, September 09, 2013
2005 (earliest)
Because how sexy do you feel right now, really? Pretty good. Our audience is feeling pretty sexy. OK, but I know a lot of you are at home watching me right now in your schlumpadinka pajamas.
—Oprah Winfrey, “Releasing your inner sexpot,” The Oprah Winfrey Show, May 31, 2005
This Oprah-coined term appears to be a playful variation on the Yiddish term shlumperdik, "dowdy," from which we get the word schlump, "a slob; a slovenly person."