"If you said, “Hey! That’s a TCP header diagram in Lego(TM)”, or perhaps, “Holy &^%@! That idiot made a TCP header diagram in Lego(TM)!”, then you’re exactly right! This is another one of those wild, wacky ideas that we dreamed up in the middle of one of my SANS classes (note to the SANS staff: shorter breaks might be a good idea). I bet my students never thought I’d actually do it.""
Link to Original Source