An April 1990 amendment to the Constitution of Wisconsin.
The governor of Wisconsin has the power to invoke the line item veto, striking portions of a bill while keeping the rest. This can be a very useful tool for eliminating riders and pork barrel spending. Rather than having to veto the whole damn bill and sending it back to the legislature to fix, the governer just removes the offending part and signs the remainder. This gives him a bit more power, as he doesn't have to keep sending it back to the legislature until they get it right or override his veto.
Former Wisconsin governor Tommy Thompson, however, took this to the extreme. In one bill he completely reversed the meaning by striking the word 'not' in the middle of a sentence. Another time, he removed parts of words such that the remainders formed completely different laws from what the the legislature had written. (Though the Wisconsin Supreme Court had ruled that the resulting laws must be germane to the subject of the original bill.)
The public didn't much like this, and the legislature certainly felt the same way. So they passed what became known as the Vanna White Amendment to the Wisconsin constitution. Article 5, Section 10 of their constitution now states:
(1) (a) Every bill which shall have passed the legislature shall, before it becomes a law, be presented to the governor.
(b) If the governor approves and signs the bill, the bill shall become law. Appropriation bills may be approved in whole or in part by the governor, and the part approved shall become law.
(c) In approving an appropriation bill in part, the governor may not create a new word by rejecting individual letters in the words of the enrolled bill.
Exactly how this addresses the problem of ol' Tommy boy striking out the word 'not' to negate a bill, I'm unsure.