A even lower use of the "threesome". It's when someone takes a traffic cone, shoves it up a
girl's vagina. Then, she stays stiff as a board. On the "ass" side of the
girl, a
guy gives her anal. Another
man lies on the "head" side of the
girl and lies down, his erect penis along the same line of the girl's mouth. When the man on the "ass" side of the girl reaches the ground he pushes up with his legs, causing the "head" side of the girl to go down on the other guy's dick, performing a blowjob. This goes on until all three (that's important) members of the sex act cum.
If you want to
find the best example to convince your guy
friend to have a
threesome with you and your girlfriend, the Morrocan Seesaw might want to be included as a possibility.