A guy's prostate — the walnut-size gland under his bladder — is the ultimate magic button to push if you want to blow his mind in bed. To tantalize it, partway through oral sex or intercourse, rest two fingers against the swath of skin between his testicles and anus. "His prostate is situated above your fingers, inside his body," says Kerner, "so by applying pressure here, you're indirectly rubbing his G-spot." When you sense he's close to orgasm, rhythmically press the area (one pulse every second) until he climaxes. -Cosmo