Awesome! Looks like mother nature may have called in sick that day. Do I see 3 stamens also? Maybe you can attribute it to a biological oddity. Much like the possibility of having triplets. Is it possible? No, but that doesn't rule out that small percentage of possibility. Glad you took a picture, as it is worth a thousand words.
Ed

I didn't notice the three stamens until you pointed them out. It is growing in the same pot as the fuschia colored hibiscus. I hope i get more blooms like this one, but i doubt it.

Another item of note is it appears that there are only pollen 'sacs'. How unique!

keep an eye out and see if this happens again on the same branch.