We used to sneak alot into the football stadium in college in ziploc bags under our clothes.
If you get near your limit you can always try that...
(actually, I just found this:
If you stay more than 48 hours you are allowed to bring back goods up to $200.00 (Canadian). If you stay more than 7 days, not counting the day of departure, you may claim an exemption on goods up to $750.00 (Canadian) not counting alcohol and tobacco. These goods are not required to accompany you.
Permitted in the $200.00 and $750.00 exemptions are up to 50 cigars, 200 cigarettes and 400 grams of tobacco. You may also bring back 1.14 L of alcohol, 1.5 L wine or 8.5 L beer or ale or 24 cans.
I was busted driving into the states once with too many bottles and the hard-case immigration guys poured it out. Bummah! I had been in Mexico for a couple years with my car so they checked, like, everything twice.
I think the downside is loss of liquid, not anything tough. Especially with those polite mounties up there, eh.