Is a unprofessional part time job such as this something that should be included on a professional resume and if so how should it be displayed?
I would leave it off. Other than conveying "I need extra money to make ends meet, and I chose a non-professional way to get the cash", it doesn't add any value.
Your resume should present your skill and accomplishments in the best light possible, in order to attract attention and ultimately get you an interview from potential employers.
I suppose you could stretch it to imagine that someone would be impressed by how hard working your friend might be. But in general adding unskilled side jobs doesn't make your friend more appealing to someone looking to hire a professional developer.