How Do You Get Out Of Tahm's Belly?

Hey there. It said in the notes when they were releasing that when he eats an ally the ally or Tahm could chose when/where to get out. I was eaten a few times in a game recently and was not fining that anywhere. So how do I get out of a trolls belly/ when he eats me and wants to send me into the enemy team?

ps: I LOVE the music from the Tahm Kench loading screen.