Slang term used to describe an older slang term of being "square" which was often used to indicate akwardness or someone who is completely odd. If you put the letter "L" and the number "7" close enough together, the two characters create a shape resembling a square.
I got lost in the city and ended up in an unfamiliar neighborhood where I felt completely like an L 7.
by Jack Scotty March 23, 2006
L 7 was used in the 50's/60's to represent being "square" or old-fashioned or un-cool. (People would hold up their thumbs and forefingers to create a square shape as a non-verbal representation.)
In the song "Woolly Bully" one of the lines is "Let's not be L 7, come and learn to dance.
by Anne Price March 14, 2006