Literally the only way I could see that working is if they had an ear wax issue. The baby oil would loosen it up... the point of the garlic... an all natural ear plug? I think you might just end up with stinky ears...
Sticky smelly ears. Imagine the cure was in our fridge the whole time I know it can be tempting to try anything.
Interesting, first a vampire repellent and now a t cure. Garlic is powerful stuff! I think, maybe, your friend has reactive t and the garlic was a perfect sized earplug to block sound XD