Like most people my age, I really hate old people. Habitually busing home hungover in the morning/afternoon from friend's couches lead to being on buses full of disgusting old people. There was a lady who had one long nail that she was using to pick her teeth with and then she'd suck it clean, quite loudly. There was an old man who had his tongue hanging out the whole time trying to taste his chin, and the whole bus smelled of feces.
Less obvious forms of displayed dementia include rude, cantankerous old fuckers who think that simply surviving this long has given them some sort of over-entitled status. Doors must be held open despite full motor abilities and/or a mechanical "handicapped" door opening button. Seats vacated for them despite other seats being readily available in designated priority seating areas. Or in the bar I work at, service given to them before younger, more generous tippers. NO THANKS! You think giving me a quarter after ordering a round for your old cronies is doing me a favor, you classless, ignorant fucks. That 25 year old next to you who leaves me at least a buck per drink is getting served first, and I don't care if you've been standing there longer!