Onamatopoeia. Sound a cash register makes. Used tfor something worth a lot of money. Example: Are you feelin' all ka-ching? (As used on UPN's Dark Angel.)
KA-CHING (OR CA-CHING)
Meaning of KA-CHING (OR CA-CHING) in English
Slang English vocab. Английский сленговый словарь. 2012