When a female or male is "courting" two or more partners at the same time. It's basically a more polite way to call a person a slut or comment on lack of character. Referred to especially when said person "multitasker" has a current relationship with someone else. Multitasking is considered the gateway to cheating and can also be considered cheating.
Tom: Wow, Susan has a boyfriend, yet she's talking to two other dudes.