Most of the bumpers I remember hearing were quick, animated, and consisted of several vocal effects and fun sounds. I used the first 10 seconds of this video to help inspire the writing and speaking style I’d use. Then I recorded myself with my apple headphone mic.
Once I had a decent recording in Audacity, I added the echo effect in some places and searched through a couple of tutorials to figure out how to give my voice that ‘through-the-phone’ quality in other places. I found a solid hip-hop beat and some game show sounds on Freesound which I clipped, arranged, and even reduplicated. I had to speed up most of the sounds to match my rushed speech. It kind of morphed into an advertisement.