Haha, that's funny
You say 'haha, that's funny' when your mom says 'u mum when' and you're like 'what the heck is that?' and you're in so much pain.
'haha, that's funny' when my mom said 'u mum when' and I had no idea what that meant.
'haha, that's funny' when my mom said 'u mum when' and I felt like I was going to die.
'haha, that's funny' when my mom said 'u mum when' and I had to ask what that meant.