UPDATE -- 5/27 5:40 PM: Amanda Bynes took to Twitter Monday to set the record straight when it came to allegedly lashing out at Rihanna.

"I saw a bunch of mocked up tweets about me bashing Rihanna in my mentions," she tweeted. "I'm followed by so many people that someone is always mocking up fake tweets so I feel the need to address them! Rihanna and I met and I'm sure we'll be in a music video together one day!"

PREVIOUSLY: Amanda Bynes went on a vicious, unexplainable Twitter tirade against Rihanna on Sunday.

According to TMZ, Bynes posted a series of angry tweets about Rihanna's looks before promptly deleting them.

"Chris Brown beat you because you're not pretty enough," she tweeted. "No one wants to be your lover so you call everyone and their mother."

Rihanna shot back, "Ya see what happens when they cancel Intervention?"

Bynes responded again, "unlike your fugly faced self I don't do drugs! U need the intervention dog! I met your ugly face in person. U aren't pretty u know know!"

She deleted that tweet soon after too.

While it's unclear why Bynes lashed out against the singer, we can't say we agree with the assessment. Rihanna has been posting tons of Instagram pics-- like this one of her dressed up as Marilyn Monroe-- and we have to say, girl looks FIERCE.

See part of the exchange below:

http://i.huffpost.com/gen/1158095/thumbs/o-AMANDA-BYNES-RIHANNA-570.jpg?2
amanda bynes rihanna