A mishap.

Catelyn pulled the dress up, and regarded herself for a moment, then shook her head, and disrobed. Tyrion gave his knob a quick tug as he regarded the Lady Paramount of the North's form as it came back into view, giving a little groan. This was, perhaps a mistake, for Catelyn glanced over his shoulder suddenly, as if she heard something. Tyrion could likely have escaped notice... if he had not awkwardly backed away in such a manner that the door reared open. Catelyn turned and Tyrion found himself facing one angry, disrobed Lady Paramount of the North.

Catelyn regarded the dwarf in a fury that only grew as she realized what he'd been doing. "You... you little... how dare you! Tell me why I should not tell my husband and let him strike your misshapen head from your stunted body?"