I've been over to her house before and it's not like her parents don't know me. My parents allow me to go over her house just not let guests over our own house.
Answers (1)
first ask your parents if they would allow you to go over and then ask your friend! most people wont mind their friends asking to go over to their house in fact some of the time they are too nervous to ask you and they appreciate it that you've asked them!
if he/she has been your friend for 6 years they shouldn't mind at all! just first suggest a sleepover not indicating where and if they ask about the location tell them that your parents wont allow guests over they should understand and might invite you over to their house!
hope this helped!!!