Never done it myself because I'm a narcissistic starfish who can't get a girl.
But, my friend told me he told his parents they were going downstairs to "watch a movie" and did it that way. Not sure if his parents knew, let alone HOW he convinced this girl to do that with him. They were only sophomores in highschool.
Then there's ME over here, who can barely even get a girl to hold his hand, let alone do something like that. Jeez.