This 4-minute song about a day of the week demonstrates the incredible power of social media marketing.

If you’ve watched any TV in the last few weeks or visit websites such as YouTube, you can’t miss the phenomenon that is Rebecca Black’s “Friday” - even if you wanted to.

In case you haven’t seen or heard about Black, she’s a 13-year-old Southern California teen whose parents paid a so-called vanity record label about $2,000 to write a song, have their daughter record it and shoot a music video built around it.

The result, “Friday,” is a dance-pop number that may rival “It’s a Small World” for its ability to stick in listeners’ heads - and annoy the heck out of them.

In just three weeks, it has logged an amazing 70 million views on YouTube, spawned dozens of “viral” parodies and been dissected on websites ranging from the Los Angeles Times to Entertainment Weekly.

Few people seem to like the song - it rates only 1.5 stars out of five on YouTube - but that doesn’t matter. By some estimates, she has earned $75,000 for it so far, thanks to iTunes Store sales and online video watching. Not bad for a song about a teen whose biggest life problems are waking up on time and deciding which seat to sit in for the drive to school.

The single’s success has amazed -and distressed - culture critics and pushed Charlie Sheen’s meltdown from the top of Twitter.

So what does any of this have to do with HVAC or sheet metal? It speaks to the incredible power of viral marketing. At almost every convention I attended last winter, session speakers told contractors they needed to be on YouTube with videos that showcase their company’s expertise. A quick search of YouTube for “HVAC” brings up 24,000 videos, with thousands more in related subjects such as “duct” and “refrigeration.”

None of them approach the multimillion views of Black, but several have well over 100,000 viewings, proving that people do use the Internet to seek out videos on subjects such as air conditioning. Making a good-looking video does take some time, but it is not as expensive as you might think.

When you’re looking at your advertising budget, consider investing in some videos for your company’s website or YouTube “channel.” I think you could be happy with the results.