Sleepovers w a boy

My guy friend and I are really close to the point where we have casual sex and stuff but we are friends. My mum has this ridiculous rule that I'm not allowed to sleep over at boys houses even if we are just friends. 
We want to hang out and he's moved a fair distance away (2 hours by public transport) and I plan on going and staying the night does anyone have any tips on some small white lies I can tell my mum about my whereabouts like idk what to use as a cover story. If you can help me I'd love you forever xxxxxxx