Watch the On The Chord online guitar lesson by Jeff McErlain from 50 Eclectic Blues Licks You MUST Know
Here is a quick little lick that reminds me of a big band horn part. Those cool little melodic stabs that punctuate a part of the tune.
I am just outlining a C7 chord with a few embellishments, most notably the flat 3 to the natural 3. This move is super common to blues guitar, so much so that I don't even think about it when playing. But I certainly remember when I discovered it!