We're all guilty of spending too much time on Facebook, Twitter, or Pinterest sometimes, so why not get paid to put your expertise to work as a side business idea? Lots of companies, especially startups or those in retail and travel—even influencers have heavy social media presences and are constantly in need of people to help build their brands online. You can find these types of opportunities on sites like Flexjobs and CareerBuilder and most employers on these websites are conditioned to working with people who operate these services as their side business idea. Over time as you grow in your ability to leverage various social channels, you can add more service offerings like running high-return Facebook Ad campaigns or hosting lucrative sweepstakes competitions for the brands you want to work with.
If you are an experienced public speaker yourself and know the tricks to keep calm and deliver a strong presentation, you can provide guidance for someone else who hopes to do the same. Outside of one-on-one coaching; you can create general guides, and make short video presentations on body language skills clients can use to become better public speakers.
I surprisingly get a lot of people asking to detail their car. I never intend to make a business of it, but I love doing it to my cars and people ask me to do it to theirs. All it takes is a cheap orbital buffer (mines a used craftsman) and a shop vac. I normally get easily $100 for a basic wash/wax/vac, or $200 to remove scratches and polish then wax the car.