Suki Waterhouse Snaps Cute Polaroid at Sister Immy's Birthday Dinner

Suki Waterhouse and her younger sister Immy are too cool for school while posing for a Polaroid picture on Tuesday (June 10) at Blakes Hotel in London, England.

The 23-year-old model and Insurgent actress helped her little sis celebrate her 21st birthday that night, just one day after arriving back into town. She was spotted on Monday wearing her sweats while landing at Heathrow airport.

PHOTOS: Check out the latest pics of Suki Waterhouse

“Happy 21st little baboon!!!!” Suki captioned a photo she took of a Polaroid with Immy at the birthday dinner.

“Best bday celebrations! thank you @Blakeshotel @rayban @Kerznercalliva #Round
#Clubmasterwood #21 #notagirnotyetawoman,” Immy wrote on her own Instagram account.