Does oughta rhyme with vodka?
It's an imperfect rhyme, so I'm afraid notta.

But a lotta words/phrases rhyme with oughta: caught a, bought a, brought a ... and panna cotta.
Finding a perfect rhyme for vodka is trickier. The closest I could find (which is still imperfect) is 'wokka', which an Australian term for a wobble board (a musical instrument). You can also try "wocka wocka" (Fozzie Bear's catchphrase for a bad joke) or "quokka" (a small Australian macropod, about the size of a domestic cat).
As for marijuana, I've never tried it. (It's illegal here, except in the Australian Capital Territory -- although medicinal marijuana is legal throughout Australia). But I agree with what Bill Hicks said about it, back in the late 80s: "About drugs, about alcohol, about pornography -- whatever that is: What business is it of yours what I do, read, buy, see, or take into my body as long as I do not harm another human being on this planet?
And for those who are having a little moral dilemma in your head about how to answer that question, I'll answer it for you: NONE of your fucking business. There, take that to the bank, cash it, and go fucking on a vacation out of my life.”
And having said that, I'm now surprised, amused and horrified in equal measure that the
ONLY place in Australia where marijuana is legal ... is our nation's capital.

Says a lot about our politicians, doesn't it?