Severus Snape was in fact bullied by James Potter when they were in their early years at Hogwarts. Snape tried to run away from getting bullied, but he eventually became subject to James' taunts and finally James' Levicorpus spell that makes one hang upside down in thin air. Snape was also teased by the marauders as 'Snivellus' and therefore, it is very clear that he was bullied by James Potter and his friends.