If you can get away with it, don't even wear a mask or bring one in with you. Not even around your neck.
If they make you put it on at the door, take it off as soon as they're not looking.
WORST CASE SCENARIO: If they post employees at the entrance to every grocery aisle, then put on the mask ONLY when they're looking at YOU (or telling you to put it on) then as soon as you're several steps away, out of eyeshot, take it off again! Don't pretend this does no good: Other shoppers will see this.
WE HAVE TO RESIST. WEAR OUT THESE B***ARDS. Make them work for it. Don't put your head in the noose by your own power! Make them restrain you at least.
AND YES, that especially goes for the "useful idiots" who enforce this.
1. They are petty tyrants, bullies -- the good guys all refused these jobs, they moved on to other careers, telling interviewers they left the restaurant industry, etc. because they couldn't stand telling people to put on masks all day. That leaves those jobs for -- you guessed it! The bullies and psychopaths who enjoy being mean to others; those who lack empathy for others.
2. They are human and will get sick of it eventually. If the store can't find people to enforce the tyranny, they might just be forced to forget about the tyranny. Right?
And if a man sees an old lady, young lady, child, etc. being bullied to wear a mask -- stand up for them! Show some Christian chivalry. Grow a pair!