Unknown Teenage comedy movie from the 80's or 90's


Hello to all of you Movie Freaks,
can you please help me to identify the following movie?

It's a teenage Hollywood comedy movie from the late 80's or early 90's.
The main characters are a young boy and young girl both in their teenage years or in the 20's.
She's a University student who's dating another university student, both very well mannered, belonging to high society and play against each other at chess.
During the journey to reach her boyfriend, the girl meets another guy who teaches her bad manners such as: drinking a full can of beer at once by poking it with a pen or pencil and finishing with a big burp. )
At the beginning she criticizes him, she's frustrated and is disgusted by him, slowly she starts to like him and inherits his bad but destabilizing manners such as the example above.
When the girl meets her well mannered boyfriend again in his fancy apartment, he stars to play chess with her but she gets bored-out immediately, in fact, to cut out the boredom she takes out a beer can and does exactly what the sloppy guy taught her: she pokes the can and drinks the beer all in one go without any spilling and ending with a big burp.
The well mannered boyfriend is negatively surprised and shocked from his girlfriend behavior. If I remember well, she then leaves him for the bad mannered boy.

Please note that the bad mannered boy doesn't only teach her to drink the beer at once, but many other bad habits, maybe including smocking.

Who of you movie Freaks out ther can help me out?
If you you help me I owe you a can of beer )

Andrea, a Movie Freak

Thank you OHForums!
That's the movie!

I'll mark it as 'Answered' (option underneath the title for reference) then so.