<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by FWAAA:
Another easy way to identify a 757: the 757 has very long landing gear struts (because of its huge engines - it looks much more thin and lanky than the more stout (chubby? husky?) 767.
The 757 is the really long, skinny plane. 
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I had it described to me by an AA pilot as being like your favourite girlfriend:
Thin body, long legs and a big pair of.....well you can work it out!