I have friends.....

So last night my host family is telling me they are not home friday night nor saturday and if I want a friend to come over they would be good. So I ask my host sister if shell be home and she says no so im like... so I can have a friend stay the night? And my host sister replies to that with
"Yeah but that only works if you had a friend"
This results I my family laughin at me at the dinner table for a good 10 minutes.
My family doesnt believe I have friends.....
I lived here 4 months......
Are they wrong or am I.....