technically speaking
mashing is when you can't keep time with your pedal stroke by mouthing "1cat, 2cat, 3cat, 4cat,..."
and it turns into
"1Djamolidine Abdoujaparov, 2Djamolidine Abdoujaparov, 3Djamolidine Abdoujaparov, 4Djamolidine Abdoujaparov,..."
and flies can easily land on your thigh and hang out...