John Bonini is a copywriter. He uses his site johnbonini.co to market his copywriting services (it’s all serious business stuff). The site lists testimonials. One of those testimonials is by his mother:
It’s such a sweet touch. Lesson: Just because you are in the all serious business of being an online retailer doesn’t mean you shouldn’t use humor and humanness to connect with your customers.
Here is another example
I was on imgflip.com crafting a meme. Wasn’t planning on paying for the service but their nudge is really powerful and funny. Almost fell for it: