Typically I'm running late and always end up in Group C ... this translates to being stuck in the middle of two stank large individuals, not having overhead bins to put my luggage in, among other such unpleasant experiences...
So I thought I'd try something new.
The pictures illustrate my maneuver - just remember: lay low and time it right. When the ticket agent is looking down is a perfect chance to blend into Group C and start boarding.
Bon voyage!