Glossary
Chalk
Chalk is slang for the favorite in a game or market, the side most expected to win. To bet the chalk is to back the favorite. A chalky slate or parlay is one stacked with favorites, and a chalk result is when the favorites win as expected.
Chalk is one of betting's oldest pieces of slang. The word traces back to when bookmakers wrote odds on a chalkboard and the heavy favorites drew the most attention. Today it simply means the favored side. If the Granite City team is a strong favorite, they are the chalk.
The term stretches in a few directions. A slate can be chalky when most favorites are expected to win, a parlay can be chalky when it strings favorites together, and a day can go chalk when the favorites all hold. Backing the chalk just means siding with the expected winner.
Chalk overlaps heavily with public betting, since casual money tends to pile onto favorites. That popularity is already reflected in the price, which is why favorites usually pay less than underdogs.
Favored is not free
Chalk wins often, which is exactly why it is favored, but the shorter payout means a string of favorites still carries real risk. Calling a bet chalk describes who is expected to win, not how safe the wager actually is.