why focus on jungle while mid helps to level faster (plus more money), rammus have been known as the hard turtle that got fired from nintendo .
the logic of rammus is basically been tank, (people usually forget his basic damage is quite high too) so the concept of this build is basically trolling for fun by letting other hit you while they loss more health and you get to laugh at them.
in the beginning try be a bit shy, avoid any fight until you got the thorn mail on, u can start been a bit aggresive which ur opponent might try to run, if they run u hold back, but if they don't press w and attack them in the same time (range then use e to get close).
when they notice they loss more health and try to run, use e to force them to go back to you and q if they start running and you are too slow( q are basically to charge and run).
!!!remember ignite helps for the damage!!!
flash works on chase and escape

after receiving thorn mail and frozenheart (shoe if possible) you can go to their base to eat two lane of minion (close to the base tower but still a bit distance(you don't want to get tower shot), use w when eating). obviously the enemy champion are gonna corner you but this is what you plan, the 2 lane you eat consist higher value then what you loss, plus they require more champion since rammus during the period consist to be hard to kill(too hard with spike) and the minion you eat makes you higher level than them. after hex tech and other items are purchase( funny how fast ) you are basically a nightmare, i guarrentte no champion is possible to kill you (look at the rune).
so insult them