If you start writing a 6 from the top, you're making a counter-clockwise loop -but some people write a 6 starting from the bottom.. this way, it's clockwise!!. That's how my co-worker writes her 6s.. so she thought she could do it.. but when asked to write the 6 the "traditional" way, she couldn't.

The idea is your hand can't go one direction & your foot go the different direction at the very same time.