Or bring no phone. Or if you need to bring your only one phone, turn it off so that you have the choice not to unlock it and keep it encrypted. Or, if you need to bring your only one phone and you need to keep it on, turn off all unlocking methods other than password. Or, if you do have an extra phone, do what cathfish said or fill it with a million memes, but rename the file names to something like "bomb plan 1", "attack plan B" or the likes, so that the authorities are forced to spend time investigating every single troll meme.