This is a slang combination of boo and sugar, both terms which indicate someone you care about in a romantic way -- lover, girlfriend/boyfriend, etc. This means the same thing.

Where did Sugarboo come from?

If you're wondering about the word Sugarboo, it comes from the nicknames the artist/owner Rebecca Puig has for her children, Jake and Sophie. She and her husband Rick started their family business in 2005 with “the inspiration to create products that remind us of the ones we love.”

What does boo mean in slang?

US informal. someone you care about, especially a boyfriend, girlfriend, or other close friend: You will always be my boo. Come on, boo.