Today Mac Miller celebrates his 25th birthday. And never one to be shy about expressing herself, his girlfriend Ariana Grande had an adorable message. "[Happy] birthday to my best friend for life / soulmate...i love you with all my heart," the singer wrote in an Instagram caption. Though it wasn't all serious. The sweet sentiments were also accompanied by a hilarious video. In the clip, the two jam out in the car while Grande plays around with Snapchat filters. Classic cutesy couple stuff. Cue the awwws. The "Into You" singer settled on a filter that exaggerated her face, and she's clearly amused. Check it out, below.