I'll see/we'll see
When your friend says 'I'll see/we'll see' it means they're too lazy or too rude to hang out. If they say it a lot, you need to find better friends. They might also say 'I'm busy' which is just a fancy way of saying 'I don't want to talk to you.'
'I'll see', said after you asked if they wanted to go to the mall
'We'll see', said when you invited them to your birthday party
'I'm busy', said when you texted them at 2 a. m.