Just keep a knife in the shower so you can slice the bottle open and scoop out the last bits with your fingers. Problem solved.
Discussion
I do this, but not IN the shower. Sharp knife, water and possibility to slip...
My knife isn't a grower is... For the shower
Normal people just keep a shower gun. That is going to create other problems if you use it resolve the shampoo situation.
I just open the shampoo top though, put a little water in, and shake it. That makes it easy to get the rest out. It is mixing with water on your head anyways 🤷♂️
Not a bad idea. You can imagine you're waterboarding the shampoo while you do it so you don't feel like less of a man for not using your weapons.
bonus: if you slice yourself open trying to wield a slippery soapy knife in the shower you won't have a big bloody mess to ckean up b/c it will all rinse down the drain. win/win
I keep the bottles upside down when it reaches that annoying threshold