Lean Back Means Payback
The majority of plane seats are tiltable, allowing you to encroach on the space of the person in front of you. Who would make such a threat? This woman appears to be one who would.
The man sitting behind the woman in question was apparently dissatisfied with her attempts to rest her head on something. He ended up resting his forehead on the back of her seat. This, however, must have been extremely annoying for him. “If you lean your seat back this far on flights,” wrote the person in the caption, “then f*** you.”