Going to Canada or Mexico does not have any implications on the 90-day limit. The I-94 will remain in your passport. You may be able to sweettalk a DHS agent, but this is just a tad more likely than winning $100m in the lottery just in time to bribe someone.

In reality, you'll have to leave the US/Canada/Mexico and then re-enter. Even this advice isn't perfectly sound (as there are other limitations to stays on the visa waiver program), but it usually works.