How To Block Users On Specific Offer Walls With Shiftcode?

For one user with username=Chris, where == means 'equal to'

{~if {~$user.username~}=='Chris'~}

//Code for blocked user

{~else~}

//Code for everyone else

{~/if~}

For multiple users with usernames Chris & Kathy where || means 'or'

{~if {~$user.username~}=='Chris' || {~$user.username~}=='Kathy'~}

//Code for blocked user(s)

{~else~}

//Code for everyone else

{~/if~}