Green’s Dictionary of Slang

(drugs) one microgram (one millionth of a gram), the basic measurement of LSD. An average dose of LSD is approx. 250 mics.

1967		Underground Digest No. 1 Oct. in Verzuh Underground Times (1989) 30: [She] gets picked up by a seventeen year-old street dealer who spends all day shooting her full of speed again and again, then feeds her 3000 mikes and raffles her temporarily unemployed body for the biggest Haight Steet gang bang since the night before last.
1976		R. Sabbag Snowblind (1978) 94: Here was some dude, not even a chemistry major, coming on to you with mikes, grams, bricks, kilos and hundredweights.
1981		D.E. Miller Bk of Jargon 338: mikes: Micrograms (of LSD).
1999		J. Stahl Perv (2001) 301: I was doing 800 mics of Sunshine.
2002		Fabian & Byrne Out of Time (ms.) 144: He [...] thought dipping a matchstick in a pile of hallucinogenic crystal very unscientific. He had been using carefully measured doses of 100mics per patient, I told him we were taking ten times that amount.
2009		C. Gray Acid (2010) 125: Somewhere along the line the acid had been watered down a bit. One drop from the dropper, which should have been 100 mikes, was probably closer to 80.