So I'm currently running Waterdeep: Dragon Heist and my players got their hands on a plot-crucial artifact that comes with one random minor beneficial property  and one random minor detrimental property. I rolled on the table and got these two results:

The attuned character gains proficiency in one skill of the DMs choice.

The attuned character's appearance changes in a manner of the DMs choice.

I was hoping to somehow tie the two things together in a thematic way and wanted to get some suggestions! 

For example one of my immediate thoughts was that the attuned player would get proficiency in Perform, but they would have the prominent teeth and moustache of Freddie Mercury from Queen. 

The group I'm running this for are more on the casual/joking side of things so I was hoping for an effect that could result in some amusing moments. 

The Stone of Golorr is an Aboleth, a creature known for being semi-aquatic, deep places, slime, and powerfully telepathic. I'm sure some interesting, weird, and funny things can be derived from this.

Boost athletics and make them turn buff af. 
Boost investigation and they manifest a non-removable monocle and Sherlock Holmes hat. 
boost perception and they get literal eyes in the back of their head. 
boost religion and they get a halo. 
boost persuasion and they look like a mob boss who makes people offers they can’t refuse. 

Just a skill, or does a tool count? If so, They gain proficiency with water vehicles, and a pegleg. 

They get sleight of hand, and the goatee of Dr Strange. They get Nature and one arm looks like it’s covered in bark and the other covered in fur.

intimidation, and some facial scarring.

religion and tiefling horns.

history, and a grey beard long enough to have seen most of history first hand.

arcana, and your hair is wreathed in blue flames that shed dim light for 5 ft.

Stealth and everything they wear turns black and they always walk on tip-toes.  Or a mime  

Survival and they turn into Crocodile Dundee.