The right side of your brain controls intuition and emotional expression. The left side of the brain controls speech. So when you want to say something emotionally charged a message has to be passed from the right side to the left side. But also, emotions that you feel about yourself are passed in the same way. Sometimes these messages get confused and a for-internal-use-only self critical emotional message will be read out loud. This is why Destiny, who is literally a cuckold, says the word "cuck" so much.