for one minute on a given subject (which they are normally not informed of in advance), without "hesitation, repetition or deviation". Over the years, the application of these rules has been inconsistent, and their interpretation is the focus of much of the comic interplay between those appearing, who often challenge the chairman's rulings. In the early years the rules were more complicated, as special rules were sometimes tried out in addition, on a one-off basis: a ban on the word "is" might apply in a round, for example. But the three basic rules have always applied. "Hesitation" is watched very strictly: a momentary pause in speaking can give rise to a successful challenge, as can tripping over one's words. Even pausing during audience laughter or applause (known as "riding a laugh") can be challenged. "Repetition" means the repetition of any word or phrase again and again, although challenges based upon very common words such as "and" are generally rejected except in extreme cases. Words contained in the given subject are now exempt unless repeated many times in quick succession, although this was a later addition to the rules. Skilful players use synonyms to avoid repeating themselves. Even letters may not be repeated; for example, the term "BBC" must be avoided, as it can be successfully challenged for repetition of "B". "Deviation" originally meant deviating from the given subject, but gradually evolved to also include "deviating from the English language as we know it", "deviation from grammar as we understand it", deviating from the truth, and deviating from logic. Nevertheless, leaps into the surreal are usually allowed. A panellist scores one point for making a correct challenge against whoever is speaking, or the speaker gets a point if the challenge is deemed incorrect. If a witty interjection amuses the audience, but is not a correct challenge, at the chairperson's discretion the challenger can nevertheless be awarded an extra point (the "bonus point" rule). A player who makes a correct challenge takes over the subject for the remainder of the minute, or until he or she is successfully challenged. At the discretion of the chairperson also, a challenged player can be given a "benefit of the doubt" and keeps the subject if what he or she was saying appears to remain within the rules, even if verging on their very limits. The person speaking when the whistle blows after 60 seconds scores