Oprah Winfrey -- I'll Fix Your Crapper ...

She might be rich as hell, but Oprah Winfrey proved she'll still get into the s**t ... at least when her toilet breaks.

O's BFF Gayle King posted a pic showing Winfrey getting elbows deep into the back of the crapper at her Maui home -- the same place where Michelle Obama recently celebrated her 50th birthday.

King tweeted, "Stars they are just like us @Oprah at her other job plumber ... who knows how to fix the toilet."