Context #1:
Gina: Hi, Will! It looks like you caught some rays on the weekend.
Will: I sure did! My friend and I went to Huntington Beach on Saturday. We played in an all-day beach volleyball tournament!
Context #2:
Linda: Joan, where were you?
Joan: Oh, it is such a nice day. I went out to catch some rays.
Linda: I see that. Did you fall asleep?
Joan: Yes. It was so warm and comfortable.
Linda: And were you reading?
Joan: Yes! How did you know?
Linda: It looks like an open book fell on your face; the bottom half of your face is pale and the top half is tanned.
Joan: Oh, no!
Meaning: To be in the sunshine. In this case "catch" means receive and "rays" means the sun's energy. If you "catch some rays," then, you are outside on a sunny day. For most North Americans, "catching some rays" is a positive, healthy experience.