Hello, there! Not a weird question at all! In fact, it has been asked before.

Check it out here, one of our lovely moderators has linked some good responses.

https://www.reddit.com/r/AskHistorians/comments/6x497n/is_it_possible_for_a_living_person_to_be_a_blood/

Credit: /u/commiespaceinvader, /u/Searocksandtrees.

Cheers.