A E I O U and sometimes W

I love any song where the performers crack themselves up. I don't imagine that Afroman's 'Cause I Got High song is honestly meant as an anti-drug polemic, but they have no hope of convincing anyone when they are laughing their way through the chorus. The D12 song My Band is funnier on every listen. They barely hold it together until the end, when the final teary-voiced "Fuck Marshall" breaks them all up.

Also, an Eminem song will never let you down during a workout.