Halloween // Blood drink for halloween

Hi wondering if anybody has heard about this or not, so last Halloween I read a post from this guy who went to a costume party with i his family for Halloween and they brought this red colored syrupy dink to the party and added something to it to make it have an irony taste (similar to blood). Does anybody know what he could have possibly added to make it taste like this? If I remember the drink was non alcoholic and made with corn syrup and grenadine. Ty