What is Fuckmonster?
1.
A phrase almost exclusively used by men talking about women.
A girlfriend with an absurdly high sex-drive, which initally seems great, but then you realise it's far higher than yours and you can barely keep-up, you can't sleep, you've no energy, you feel like death and STILL SHE WANTS MORE
James was overjoyed with his new girlfriend, but soon found-out that she was a fuckmonster.
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2.
A relationship definition somewhere between "friend-with-benefits" and "disease trader."
Ro Bag: "I'm not Katy's boyfriend, I'm just her Fuckmonster!"
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3.
One who frequently engages in carefree sportfucking without regard to commitment, reason, or partners' emotions.
Yulia: William is a dirty, dirty fuckmonster.
William: You know you love it.