What is the most commonly used mnemonic for spectral classification?

The most commonly used mnemonic for spectral classification is "Oh Be A Fine Girl/Guy, Kiss Me," which helps remember the sequence of spectral types: O, B, A, F, G, K, M. Each letter represents a class of stars, ordered by decreasing temperature and increasing wavelength. This mnemonic is particularly helpful for astronomy students and enthusiasts in recalling the order of stellar classifications.