A strike is a term used in bowling to indicate that all of the pins have been knocked down with the first ball of a frame. On a bowling score sheet, a strike is symbolized by an X.
When all ten pins are completely knocked down with the first ball (called a strike and typically rendered as an "X" on a score sheet), a player is awarded ten points, plus a bonus of whatever is scored with the next two balls. In this way, the points scored for the two balls after the strike are counted twice.
Strike scoring works similarly for five-pin bowling, except strikes are worth 15 points rather than 10 (as the pins are scored with the values of 2, 3, 5, 3, and 2).
Two consecutive strikes are referred to as a "double" (or a "Barney Rubble" to rhyme) aka the "rhino". Three strikes bowled consecutively is known as a "turkey". Any longer string of strikes is referred to by a number affixed to the word "bagger," as in "four-bagger" for four consecutive strikes. ESPN commentator Rob Stone created the name "hambone" to describe four consecutive strikes.
When a player is "on the strikes", a string is often referenced by affixing "in a row" to the number of strikes bowled consecutively. Six strikes in a row are sometimes referred to as a "six pack". Six strikes and nine strikes in a row can also be referred to "wild turkeys" and "golden turkeys" respectively. Any string of strikes starting in the first frame or ending "off the sheet" (where all of a bowler's shots from a certain frame to the end of the game strike) are often referred to as the "front" or "back" strikes, respectively (e.g. the 'front nine' for strikes in frames 1-9, or the 'back six' for strikes in frames 7, 8, and 9 with a turkey in the tenth). Twelve strikes in a row is a perfect game; 36 consecutive strikes constitutes a 900 series.