Have you ever had the carpet tack poke through the carpet when you step on it and poke your foot?
Carpet tack is a little thin strip of wood with nails sticking up. It is placed along the edge of walls (and in my case the doorway to the bathroom as it changed to tile). When carpet is installed, it is stretched and hooked on the carpet tack nails to keep it tightly stretched across your floor.
I recently purchased a home where this was happening in the doorway to the bathroom. There is a strip of carpet tack along the threshold of the door that grips the carpet. When you step on it with your bare feet in certain positions, there is a enough pressure to push the carpet down and expose the nails in the carpet tack so they poke your foot. Rather annoying and kind of embarrassing when you have company.
Anyhow, I read up on-line for solutions and there were a few of them. What I ended up doing was the cheapest of them all. All the spots where I could press my thumb down and feel the point of the nails, I took a hammer and hit it down. The carpet is depressed along the threshold now (it was already) and the pointy carpet tack is now gone.
I have heard you need to be careful when hammering it down. This is what is holding the carpet tight here. So that won’t be the case anymore. If it is tight on either side you should be okay. Be careful to not pull the carpet out from under a transition or hit whatever flooring is along that border (hardwood, tiles, etc).