This big spender was so sure he pulled a fast one on his dinner date , until his waitress foiled his plan. What's the biggest tip you've ever given? For most of us, it might be a $20 bill on a day you're feeling extra generous and flush with cash. It always helps out servers to tip, since their base pay is not usually very high. And of course, since servers rely so heavily on tips, big tippers make their entire day! This waitress rode an emotional roller coaster as she served this couple their…