The Fried Liver Attack is brought into action after:
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 d5 5. exd5
If Black now plays 5...Nxd5 then 6.Nxf7 is the Fried Liver.
I mention this because many people think 4.Ng5 is called the Fried Liver Attack.
After 5.exd5 there are other known paths Black can follow before a Fried Liver appears.
5....Na5 the so called Main Line with it's many braches.
5....b5 The Ulvestad
5....Nd4 The Fritz (named after a German lad called Fritz, not the wee electronic toy.)
One game I know of (which has happened both OTB and in corress chess)
is this line where White castles into it.