Webster's : Cahoot is used almost exclusively in the phrase "in cahoots," which means "in an alliance or partnership." In most contexts, it describes the conspiring activity of people up to no good. (There's also the rare idiom go cahoots, meaning "to enter into a partnership," as in "they went cahoots on a new restaurant.")
1.) To be in league with a crime, or conspiracy. Also to mean in alliance with or secret partnership with.
2.)To be a lover, or someone you like very much. Commonly used by someone how is annoyed or displeases with someone else.
(Note: this is slang, coming from the word/slang "ca" meaning: used to express a certain feeling of fondness for a person. Also the words "hoots" meaning: the characteristic cry of an owl)
Examples "Don't trust anyone on that road there are often robbers that are in cahoots with each other!"
Stu Spelling Bee 