(TMZ) Chris Brown’s GF is scared to leave her house without bodyguards by her side — and she’s telling friends, it’s all because Rihanna’s crazy fans are threatening to kill her.

In case you missed it — there was a lot of speculation last week that Rihanna dissed Karrueche Tran on Twitter — posting a pic of a bag of rice cakes wearing sunglasses … with the caption, “Ima a make u my b****.”

The joke — Karrueche’s Vietnamese … rice cakes … etc.

But several of Rihanna’s fans took the joke one step too far — unleashing an avalanche of violent threats on Karrueche … like “I hope Rihanna beat the dog shit outa yo ass!” … “Watch yo back” … and “I will kill you.”

Rihanna never admitted the rice cake jab was directed at Karrueche — but sources close to Karrueche tell TMZ, she now refuses to leave her house without Chris Brown’s hired muscle by her side.

As for Karrueche’s infamous BF — we’re told CB is 100% supportive of his new lady … despite getting close with Rihanna recently … and is urging her not to worry