"@rihanna Chris Brown beat you because you're not pretty enough," Bynes tweeted, going on to say, "@rihanna no one wants to be your lover so you call everyone and their mother that I almost named my new dog Rihanna."
Bynes quickly deleted her tweets…but it looked like Rihanna had already caught wind of the Easy A actress's insults when she wrote this just moments later:
"Ya see what happens when they cancel Intervention?"
And even without a Twitter mention from Rihanna, Bynes got the message, firing back with,"@rihanna unlike ur fugly faced self I don't do drugs! U need the intervention dog! I met ur ugly face in person! U aren't pretty u know it!"
The duo's feud stopped there, with Rihanna making no other comments in reference to Bynes...at least for now.
Rihanna is just the latest celeb to beef on Twitter with Bynes, who most recently got into a spat (and then made amends) with Jenny McCarthy.