Some of the advice in this thread seems really off. I have had my phone searched by customs in the US before (many many years ago). But contrary to the statements in this thread, they weren't fishing for a reason to deny me entry but rather seeking confirmation that I was genuine in order to admit me.
Also, nobody in this thread has acknowledged the critical point that CBP say drug use was the reason for the denial, not the meme -
source:
Of course, the agent may have been less lenient on the drug use because they saw the meme and took a personal dislike to the passenger - but that applies both ways. The sensible advice is not to have divisive content on your phone when you may be relying on someone's discretion or arriving with a borderline case.
If other people want to avoid the US, that's fine by me though... probably explains why I've been able to find such cheap flights