1.   The mole burrowed its way under the ground.

2.   Gridlock has metastasized into a daily menace, burrowing its way into the daily fabric of home life and workplaces.

3.   The name itself has burrowed its way into the popular lexicon, and in an age fascinated with the tawdry side of life, is a tabloid headline word.

4.   They burrowed their way into the underground cache.

5.   Why has the three-minute pop song burrowed its way back into the national consciousness after all these years?