You must stay in the US at least 48hrs to include alcohol in your personal excemption when you come back to Canada.
Youre allowed to bring back (free of duty):
1.5 litres of wine
1.14 litres of liquor
a total of 1.14 litres of wine and liquor
OR
24x 355ml cans or bottles (maximum 8.5 litres) of beer.
The exceptions are also personal (your friend cant transfer his excemptions to you). In addition, your duty free excemptions for goods other than alcohol/tobacco are: 24hrs ($50), 48hrs ($200) 7 days ($750).
For anything else:
http://www.cbsa-asfc.gc.ca/E/pub/cp/...44-e.html#P035
Cheers.