Is there such thing as a z cup?

Yes, a Z cup size does exist, although it is quite rare and not commonly found in standard lingerie sizing. Bra sizes typically follow a lettered system that can extend beyond D, with larger sizes like DD, DDD (or E), and so on, potentially leading up to Z in some brands. However, the availability of such sizes may vary significantly, and many manufacturers may not produce Bras in those sizes.