I don't drink Tea or Coffee, so I only get Caffeine from fizzy soft-drinks.
I never ever find that they put me on any sort of high though.
I don't feel buzzed, or anymore energetic. It's just like drinking any other drink for me, just it tends to be sweet and flavoured.
My younger brother however is and always will be a little stuff when he's had Coca Cola.
Not so bad now that he's 16, but it used to send him up the loving walls before.