Welcome, Laudenum.
Bet you can’t stay just a month!
Francophone here.
First you’d have to let us know where you heard it: Quebec or Europe ?
Petit joue is non-existent
Petit jouir is certainly not French
Petit jouet, little toy, is not an insult, or it might be a mild insult you tell a woman “tu n’es qu’un petit jouet” (you’re but a little plaything").
Petit chou should not be translated as “little cabbage”. It’s never understood that way. It simply means “little darling”.
I don’t think I’ll have a choice 
I’ll make the most of my time here though. 
Hi Gymnopithys, it was France French. The definition given by Busy Scissors seems to fit the context but if you have any other thoughts I’d be glad to hear them.
Do your best to make a good impression, and then post a request in the Request to Sponsor My Membership thread, and you may find that it’s not entirely up to you.
Maybe it was really petit chou but meant sarcastically?
The expression is “petit joueUR”. Literally “small player”. It would conjures the image of someone who would place a ludicrously small bet during, say, a poker game.
So, it could refer to someone who isn’t daring enough, or isn’t in the same league as the person uttering the insult, or isn’t performing enough to be taken seriously. In any case, an expression of despise. In French, I would say it’s relatively similar to “minable”. I’m not sure how to translate it in English. Maybe simply “loser”.
That’s my guess. Like, “Sayonara, sweetheart.”
Or . . . perhaps the key word was petit. . . .