They give you a PIN number on your first visit. It is your duty to remember it.
You can't ask anyone for their code. Their code is assigned to one person and only that person can use it. They already know about people who don't go there anymore or perhaps had an altercation that that customer might give their code away to randoms out of spite.
So now they tie phone numbers to pins. So even if someone is willing to lend you their pin, if it doesn't match the phone number on file, no go.
I hate sounding like a broken record but be honest. If you forgot your code, call them and tell them that. Don't try to go around it. They already blacklisted someone who somehow got in by lying.
Don't be like that guy.