don't tell them you were hanging out with your boyfriend, danggg that will just get you in trouble lol
i agree with you checking the mail, maybe saying you were expecting something from a friend or whatever
or you wanted to look at the stars
or you heard a weird noise, or saw a cat, or you just wanted to sit outside to get some air
or maybbbbe say you had a headache, and wanted to sit outside or something
i go outside a lot a night, usually just to get a change of scenery from inside the house
if your parents do catch you, make sure your boyfriend has a hiding spot already picked out so he can go there when they come out.. lol
and just be calm about it, if you're nervous they'll think you're up to no good~