What does "go in when my stun is up" mean in League of Legends chat?

Q: What does "go in when my stun is up" mean in League of Legends chat?

It means "Go in when my stun is up.". "up" means available. The support announces the condition for engaging: his crowd control. The adc waits for that signal instead of guessing.

team chat

what you want to say

Go in when my stun is up.

what you type

go in when my stun is up

the context

A support telling their ADC when to engage.

What it actually means

"up" means available. The support announces the condition for engaging: his crowd control. The adc waits for that signal instead of guessing.

Related lines

wait my ultWait for my ultimate.
trade when he uses qTrade when he uses his Q.