Green’s Dictionary of Slang

1. (US Und.) anything illicit, esp. drugs, money, a weapon, stolen goods etc.

1950		Goldin et al. DAUL 132/2: Mahoska. 1. Habit-forming drugs. 2 A pistol or revolver. 3. (P) A knife or similar weapon. 4. Anything illicit or necessarily secret, known only to the parties involved, as stolen goods, combustibles, and counterfeit money.
1953		Anslinger & Tompkins Traffic In Narcotics 312: mahoska. Habit-forming drugs.
1992		Bentley & Corbett Prison Sl. 87: Blade A knife or a sharpened object used as a knife. (Archaic: mahoska).
2018		D. Mamet (con. mid-1920s) Chicago 109: ‘[D]o you have or do you require a mohaska?’ ‘I have the Luger,’ Mike replied.

2. (US) without the article, the penis.

2003

D. Hamill Long Time Gone 165: Copping my joint so their husbands wouldn’t get pictures in the mail of them copping his best friend’s mahoska.