What is the little bump with a hole in it on the inside of my cheek?

Usually when someone asks this question they are referring to Stensen's duct. This bump, located on the inner cheek adjacent to the maxillary first and second molars, is the opening of the duct leading from the parotid salivary gland. It can be seen bilaterally (on both cheeks) and has a little hole in it that the saliva from the parotid gland can emerge from. It is completely 'normal' and usually doesn't indicate any pathology.

Occasionally the duct can get plugged with a salivary stone or localized trauma and can become painful. When this occurs the cheek can be sometimes seen to swell when a patient is eating, since chewing stimulates salivary flow from the Parotid. If the duct does become plugged it may be necessary to visit your dentist or an Oral Surgeon. Most Oral Surgeons know how deal with a blocked Stensen's duct. It may be necessary for them to cannulate it ( they can use a small needle like cannula to re-open the duct) or sometimes prescribe an antibiotic if they suspect an infection.