Your grandmother used to make your uncle and I do this any time we got a splinter or any time one of us had a cut anywhere that got infected. What you do is you take adhesive tape and put it on the infected area. Your grandma swears by it, she thought that if you did this, the sticky part would ‘suck’ out the splinter or puss and heal whatever was hurting.
This method was taught to me when I was little, and I also swear by it. Since my mother taught it to me I tell my friends to do this when they get infections and things like this.