"Reply when I feel like it."
Means: "I'll never reply. I never feel like it."
Usually the response a guy gets when confronting a female on why she doesn't reply to his messages (and try to work things out).
Can also be undertext if they tell you "I'm busy." which means: "I don't feel like it."
Jason: "I want to fix things, but you never reply, you keep saying you're busy but you're always texting your friends". Sonya: "I'll reply when I feel like it."
A response to your message that is actually relatively decent and not just k, or lol, these things can be sent but must be followed with a contribution to your statement.
"I love you" is an acceptable reply for a significant other
"Lol. I love your meme"
"K, but what about (blank)?"
Refers to a comparably-humorous but non-verbal version of three consonants and a dozen vowels, and involves using your forefingers or thumbs to manually "peel up" your eyelids and then groggily waggling your head to indicate to the person who requested your assistance that you're so weary that you can't even keep your eyelids open.
Sometimes when I ask my ordinarily-very-supportive sister about helping me with some task that admittedly I **could** perform all by myself but which would be a lot easier and/or more pleasant to accomplish with an assistant, she gives me the "eyelids-lift reply" to indicate that she feels really exhausted on that particular occasion. and so I respectfully "let it go" for the time-being, and then either wheezingly struggle though said arduous/disagreeable undertaking on my own, or wait till maybe the next day to ask my sister again if she could help me complete it.
The effect achieved when people unnecessarily reply-all to an email that only required a standard reply, unnecessarily filling everyone's inbox with unneeded crap.
There goes Jim again, constantly creating reply-all pollution. I wish he realized there are 100 other people on this email chain who don't care!
The reply-all pollution on this team is suffocating!