What is when a guy calls you his partner in crime?

When a guy calls you his "partner in crime," he's using a casual, playful expression to describe you as his close companion or friend. The phrase suggests that the two of you are dedicated allies, willing to support and help each other through the ups and downs of life. It's a bit of a slang or colloquialism, implying a sense of loyalty, adventure, and shared mischievousness. While it can also be interpreted romantically, it generally has a more platonic connotation and emphasizes the idea of a solid, trust-based friendship.