be down with (something)

be down with (something)

1. To be in agreement with, in support of, have interest in, or thoroughly enjoy some subject, activity, or thing. I am so down with math, it's my favorite subject in school! Yeah, I'm down with seeing a movie later this evening.
2. To be on friendly terms with or enjoy the company of somebody. I'm down with Cathy, we just had a small disagreement is all. I'm just not down with John, I think he's kind of a jerk sometimes.
3. To be ill or have caught some disease. (More often expressed as "come down with something.") Marigold had to go home early today. I think she's down with the flu.
See also: down
Farlex Dictionary of Idioms.

Down with

someone or something! Do away with someone or something!; I am opposed to someone or something! Down with higher taxes! Down with corporate tax breaks! Down with tyrants!
See also: down
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

down with

1. Ill with, as in He's down with the flu. The down here alludes to being felled by illness. Also see come down with.
2. Depose, do away with, as in Down with the king! This imperative dates from the early 1500s.
3. Lower or put something down, as in Down with the mainsail. [Mid-1600s]
4. be or get down with . Be close friends with, as in I'm down with that crowd. [Slang; late 1900s]
See also: down
The American Heritage® Dictionary of Idioms by Christine Ammer.

down with something

1. mod. comfortable with something; comfortable. (Usually with get.) Let’s get down with some good music.
2. mod. ill with something; sick in bed with something. I was down with the flu for two weeks.
See also: down, something
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • not stand the sight of (someone or something)
  • a head-scratcher
  • be beat
  • a (real) gas
  • (as) black as ink
  • be ripped to shreds
  • be sick of (something)
  • confirm
  • confirm (one) in (something)
  • confirmed