Walking barefoot! A fun way to explore the world with your feet but can also lead to unexpected encounters with Lego pieces, unexpected wet or sticky spots, and sharp objects, which lead to the inevitable question of, "do I need a tetanus shot?" - We usually call it a TDaP (tetanus, diphtheria & acellular pertussis).
We are supposed to be getting tetanus boosters every 10 years to prevent the infection, which is caused by clostridium tetani spores in the environment. We think about the risk as typically being when you get cut by rusty metal but it's actually much more than that. The CDC says the risk for tetanus involves risks "Such as, but not limited to, wounds contaminated with dirt, feces, soil, or saliva; puncture wounds; avulsions; or wounds resulting from missiles, crushing, burns, or frostbite." So watch out for missiles.
It's not a terribly common condition here, but in many other countries it is very common due to low vaccination rates. We actually have a rising incidence of it in older people as the immune systems loses some of it's fighting power or they've missed a dose of their TDaP. They've found that only about 1/3 of people over 70 have immunity!
Making sure you're up to date on your tetanus shot should be one of the first things checked after you have some kind of dirty injury as described above. Here, tetanus is uncommon enough that we are usually able to control it, albeit after a lot of intensive treatments in the hospital, but in other countries, it can be deadly up to half the time. If you want a summary, I heard about this case in Portland recently that highlights how bad it can be.