I'm going to pick up my check on a day I called in sick to work
Why do you want to pick up your check on that day?
Because my girlfriend also works there and they wouldn't pay her when she called in sick for having her period.
It is not good to show up for work on a day when you called in sick. People will think you are faking it and it will reflect badly on you. It might affect your employment.
I don't care if they can tell I'm not sick. I'm going to do it anyway.
You should wait to pick up your check. You might have inconvenienced your coworkers and they might be mad if they see you picking up your check on the day you called in sick.