When you and your significant other, best friend, or life partner both happen to be pirates.
Can also be a reference to a delicious brand of cereal, or a derogatory term for gay dudes.
Jim and I have raiped and pillaged together for years, were total soul mateys.
Those soul mateys I had for breakfast were delicious.
Gay marriage isn't legal yet so, Todd and I went to South Carolina where we registered as soul mateys.