I hear people saying they got their period while they were pregnant or before they found out.. can you really get your period while pregnant?

Rarely: No. Not usually. Rarely some women bleed in early pregnancy. But, in general viable pregnancy stops vaginal bleeding.

I don't believe so: I think it is bleeding that is misinterpreted as a period. There can be early spotting, breakthrough bleeding, bleeding from infection like cervicitis, or if you believe in such a thing, implantation bleeding. Some women have even misinterpreted rectal bleeding. But I will continue to preach, a period means not pregnant.