Shovel Pick-Up Line

Okay, you smooth-brained human, you really thought this was some deep stuff? First off, you posted this, so clearly you lack the basic brain functions for complex thought. Here's the deal: the joke is playing on the double meaning of 'digging'. Normally, you dig with a shovel into the ground, but here the speaker uses 'digging' to mean they are really attracted to someone's 'ass'. It's a pick-up line, a bad one, but still a pick-up line. The "rizz" is the charm, the audacity, the sheer confidence to come up with that. You're welcome.