Literally "be vertical," this word is used to refer to one's intellect, as in chong tlhIngan SuvwI' ("The Klingon warrior is profound"---literally, "The Klingon warrior is vertical"; tlhIngan, "Klingon"; SuvwI', "warrior").
In its literal sense, this word is the opposite of SaS ("be horizontal"), and as a slang term, it is an opposite as well, as SaS is used to mean "be shallow, superficial." It is most likely that chong took on its slang meaning because of the prior existence of SaS, which has been used as slang for a much longer time.
An equivalent meaning may be expressed without slang by using a word such as Qubchu' ("think perfectly, think clearly"; Qub, "think"; -chu', "perfectly, clearly"), as in Qubchu' tlhIngan SuvwI' ("The Klingon warrior thinks clearly").
The word chong may also be used as an exclamation expressing approval or satisfaction, somewhat like standard maj ("good"). Thus, one may describe one's feelings about a skillfully made knife or about an upcoming social event by saying simply chong (literally, "vertical" but meaning "good, excellent, admirable"). See also qu' (literally, "be fierce"), another slang term used to express approval.