Almost every single day, something stupid is said to me and I will say something uninspired at the time then spend the week subconsciously formulating a witty response, then lament not using it. And on the rare occasion I do say something clever, it is often drowned out by yet more stupidity. You just can't win.
Four somewhat clever things I've said at the actual time (that I can remember) are:
In response to "You look like a girl with that hairstyle" (I have a ponytail):
1. "Then it is with great regret that I inform you that you are blind in the lower 90% of your eyes."
2. "Better than looking like a fucking moron for mistaking someone with no tits and facial hair as a female".
3. "If only I had your stature, even those with common decency and a brain would be fooled".
In response to a deluded prophet-like Lebanese man who occasionally shouts from atop the stair leading to my platform in the morning (this was the fifth and last time I saw him, but I may just be lucky):
"What is the point of this? What are you trying to do? Spouting contrived and incoherent bullshit only makes you look like an idiot. If people on this platform already believe in God, then they take nothing from what you say, those who don't are probably less likely now to believe than before, and if any of them has even the briefest knowledge of how earthquakes work, what you are saying is an insult to their intelligence."
Response: "What I'm saying is the word of God, and if you can't see that you are going to go to hell." - loosely paraphrased.
I threatened to call the police and report him as a public nuisance. It has apparently worked.
And one plain intimidating thing I said only a few days ago, in response to "Hey, are you a ******?" (this said by a lowlife on the train, at night, who came and deliberately sat opposite me although he was already on the train):
"Coincidentally, no, but I have been programming for the last 5 hours and I am in no fucking mood for this. So if you know what's good for you, you'll shut your fucking mouth and move to another seat while you still have the use of your legs."
In an incredible stroke of luck, after provoking me on and off betweentimes, he chose the few minutes before my station to make physical contact, allowing me to pick up my bag, uppercut him in the gut, and walk out of the carriage in one smooth motion. I have my moments.