a little sneak sneak
When someone does something so small and sneaky that it's like they took a single step and now they're claiming they ran a marathon.
My brother snuck a snack and now he's telling everyone he's the king of the snack world.
My sister moved one piece on the board and now she says she's the best player ever.
My dad took one sip of coffee and now he's saying it's the best ever.