Skunks are mating. I can smell that spring is near because the scent of skunk is in the air. It's an unmistakable nighttime fragrance. The unpleasant olfactory sensation (skunk!) becomes a pleasant mental sensation (i.e., thought = almost spring!).
If you don't want to be skunked by your distracted mind during meditation, set your intention before you begin to meditate. Then, be diligent. Diligence requires effort. Keep applying effort, gently but firmly.
I use the Dismissing Technique: Thank you (thought) for coming. I don't need you right now. You can go now. Often, i say this repeatedly during meditation.
Otherwise the mind runs off over hill and dale, and you will be skunked in your effort to find a moment of calm.