Can you use a condom full of marbles as an anal toy?

NO. The condom could rupture, the marbles could become loose, and perchance one would fracture, potentially sending even the tiniest shard of glass into the wall of the colon causing a perforation, leakage of the bowel contents into the abdominal cavity, sepsis and death.

I know! You're trying to get on that show "1000 Ways to Die." Good luck, I hear that gig pays pretty good. Keep trying, you'll get there eventually!