Often the first (more obvious) meaning is straightforward, while the second meaning is less so: often risqué or ironic.
In case you weren't aware, International Ride to Work Day is coming up on June 18, 2012. The cheeky blokes from the UK decided to spice things up a bit (risqué it is, then...) by producing the video you'll see below. We like it. After all, riding a motorcycle or scooter to work can be a great way to change up the morning commute, just so long as it's done safely.
So, remember what mum says: "The most important thing is that you're wearing protection."