Not to be a Danny Downer- because I love my coffee (Philz Ambrosia!) - but drinking lots of coffee greatly increases your chances of colon cancer - especially as you approach your mid 30s. Enjoy that cup a day but learn to like tea too.
But also from personal experience, when I drink a lot of cups per day for several days, my shall remain nameless parts start feeling odd. Doesn't really start till you're in your 30s and later though.