I just call and say "I'm not coming in today" That's it. Don't need to give a reason.
Yeah I do this one, I just say I won`t be able to make it in, I`ll call back if I`m feeling better. Granted I never engage in this type of fraud so I my boss never gives a shit.
Anyhow you don`t need to let the boss know whats wrong when your back to work, by that time I`m usually hungover as fuck from drinking on my day off, so I just look sick and do a half ass job all day.