If you’re on the job and someone asks you to make a sign, perhaps it’s your responsibility to ask if there are implications beyond the intended purpose.
By making this sign so big, you trump all other signs in importance and yes it sends a message alright.
This may stop drinking on the job (probably not), but it tells all the future homeowners (and those shopping for a new home that are not under contract with you) that your company has a serious drinking problem. Yeah!

Obvious Drinking Problems Anyone?