Yes, you can get internet through a power outlet using powerline adapters (also called powerline networking or HomePlug).

Utility Data Signals: Some utility companies use power lines for low-bandwidth data transmission (e.g., for smart meter readings via Broadband over Power Lines, or BPL). A highly skilled hacker with specialized equipment might attempt to tap into these signals. However, BPL is rare, extremely slow (not practical for general internet), and heavily secured by utility providers.