Canada defines "inadmissible," as taken directly from the Canadian Embassy's official website:
"Members of Inadmissible Classes include those who have been convicted of MINOR OFFENSES (including shoplifting, theft, assault, dangerous driving, unauthorized possession of a firearm, possession of illegal substances, etc.), or of INDICTABLE CRIMINAL OFFENSES (including assault with a deadly weapon, manslaughter, etc.). As well, those who have been convicted of DRIVING WHILE INTOXICATED (DWI) are considered Members of an Inadmissible Class. Driving while under the influence of alcohol is regarded as an extremely serious offense in Canada.
So regardless of how minor you feel the offense was, it may be sufficient in the eyes of the Canadian Border Patrol to send you packing back home. Check it out before you go!