2. Use a falsetto voice.
3. Slow down your speaking rate.
4. Exaggerate your pronunciation of vowels.
5. Add vibrato to your voice.
6. Use a sing-songy tone.
7. Use vocal fry.
Here is an example of a sentence spoken in the style of the Adventure Time baby song:
"Oooohhhh, I'm so happy to see youuuuuuuuuuu!"