Lean on me
We initially thought that this was a funny picture of a lovely couple on a plane together. However, that didn’t turn out to be the case. According to the OP, a strange man was leaning against the OP’s mom’s shoulder for support during a long flight. They couldn’t just jolt the man awake, so they took a pic and shared it online.
OP’s mama saw the funny side of the situation and smiled for the camera. This would be the decent thing to do. However, it would be a completely different story if the man started snoring or (god forbid) drooling on her!