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1.
(language: Cantonese)
/gʌm laʊ/
(guhm lou)

–verb (used with object)
*more uses than listed*
1. Slang . to screw up.
2. Slang . to treat unfairly or harshly.
3. Slang . to jizz on (also refer to T-bag).
4. Slang . to perform act of violence.
5. Slang . to cheat.

–verb (used without object)
1. Slang . to meddle (usually fol. by sher lai bei ah dow ah).

–interjection
1. Slang . (used to express anger, disgust, peremptory rejection, etc., often fol. by a pronoun, as you or it.)
2. Slang . (to add emphasis. Usually fol. by piece of shit).

–noun
1. an act of sexual intercourse.
2. Slang . a person, esp. one who is annoying or contemptible.
3. what the fucking gum lao, Slang . (used as an intensifier, esp. with WH-questions, to express annoyance, impatience, etc.)

-adjective
1. soiled with dirt; foul; unclean: gum lao pair of shoes.
2. lacking ordinary quickness and keenness of mind; dull.
3. characterized by or proceeding from mental dullness; foolish; senseless: a gum lao question.
4. tediously dull, esp. due to lack of meaning or sense; inane; pointless: a gum lao party.
5. annoying or irritating; troublesome: Turn off that gum lao radio.
6. in a state of stupor; stupefied: gum laoed from fatigue.
Common usages:

1. "Why are you so gum lao?"
2. "I gum laoed the test."
3. "Fuck that gum lao piece of shit"
4. "Wyatt, stop gum laoing your own face" (also refer to T-bag)
5. "Stacy gum laoed your balls last night" (note ambiguity: multiple definitions)
by Justin "Gum Lao" Wan November 29, 2010