This is totally off topic, but you don't have an email address in your profile. So I'll ask it here: How easy is it for a non-student to "unofficially" drop in

This is totally off topic, but you don't have an email address in your profile. So I'll ask it here: How easy is it for a non-student to "unofficially" drop into a CS class in UW? Will the professors find out and call the security/cops? [Edit:mongoose has answered me by email. Thanks!]