eyes like a shithouse rat 

A person with exceptional observational skills, as in being able to spot items in complex or busy environments.

That lads got "eyes like a shithouse rat"

eyes like a shithouse rat by OwDo June 10, 2022

Shithouse Rat 

The saying "He is as cunning as a Shithouse Rat" is used to refer to someone who is expertly sly and/or sneaky. A shithouse rat being of a lower class than even a regular lowly rat, makes this form of cunning even more underhanded.

This term does not refer to anyone's "mental state".

Don't take your eye off him for a second! He's as cunning as a Shithouse Rat.

Shithouse Rat by Treasur-Ess September 7, 2016

crazier than a rat trapped in a tin shithouse 

Phrase old fuckers used to use to describe really fucked-up seemingly normal people. All bets are off in this situation because now this means the batshit crazy person loses their shit pretty fast and wants to fuck someone up real bad. My advice: run. The short modern version is: crazier than a shithouse rat. The clean version is: crazier than a rat trapped in a tin hen-house, but dont' even use this version around more than three women who are over 30 or they will fold their arms, lower their head a little while glaring at you --like you just offended their pussies.

That Jenkins is "crazier than a rat trapped in a tin shithouse"

crazier than a rat trapped in a tin shithouse by Jaspa J October 1, 2012