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1.
the chemical found in cough medicidnes; short for dextromethorphan, the active ingredient in robitussin, dayquil, etc. When taken in large quantities, it makes you trip; cough syrup used to robo trip
Man, I tripped balls off that dexo last night!
by emshea April 04, 2010
 
2.
(Adj.) Used to describe someone who in your opinion is very cool or crazy.
"Hey, what do you think of Dan?"
"He's completely dexo!"
by gregk May 01, 2005