Please don't do that. Please don't encourage the others to do that. It is a safety hazard and can invalidate your homeowners' insurance.
Tesla published temporary instructions that consisted of installing a 50A breaker, installing the appropriate conduit (1") with #2 or #3 AWG wiring, to the location where the HPWC would be installed. A full-size junction box is mounted there, where roughly 1' of extra conductor is installed. The #2/#3 is interconnected to a temporary run of #6 which connects to a surface-mounted NEMA 6-50 receptacle below the junction box. Tesla supplied a NEMA 6-50 adapter (in addition to the 14-50 and 5-15) for free to those who had ordered the HPWC with the car. When the HPWC arrives, the electrician simply removes the junction box and temporary outlet, and connects the HPWC directly to the #2/#3, then swaps out the breaker for a 100A breaker.
Electricians use 50A breakers all the time, so they can put them back on the truck. Even if they do charge you for it, a 50A breaker is usually only $15 or so for most panel types.
According to NEC (and I assume CEC as well), a NEMA 14-50 or 6-50 receptacle may not be connected to a branch circuit with a higher rating than 50A.