I meant to say juice, what else could it be?

Many churches use grape juice (unfermented) due to their temperance beliefs. This is beneficial, also, for recovering alcoholics who live by the rule that one drink is too many and three aren't enough.

They also call it the blood of Christ. I wasn't sure whether I had to call it that or not.

You are correct. I never did partake of communion in any of the churches I attended, but am familiar with the ceremony.