Eren froze when he felt something press suspiciously against his butt but didn't jerk or make any other sudden movements that would have endangered his precarious balance.

Turning to give the culprit a look over his shoulder, his brows furrowed lightly. "Sorry, but I think I'd rather not argue with some perverted old man." Noting this guy's strange outfit to be apparently some sort of uniform, he added a reluctant "...Sir."