What do ports do exactly? and what should I expect if I were to choke a port on a speaker?
Which speaker model do you have, and how much clearance does the manufacturer recommend for speaker placement?
Ports are used to tune the response of the woofer and increase bass. The port relieves air pressure in the cabinet so the woofer cone can move more freely, and sound is emitted from the port opening itself. When a rear ported speaker is placed close to a wall, the bass coming from the port is reinforced and reflected by the wall, which may cause a bloated sound, and in that case it may help to plug the port. Plugging the port partially or completely is a common way to tune the sound of a speaker to adjust for speaker placement and room response. Some manufacturers actually provide a port plug with the speaker to optionally adjust its sound for different situations.
In summary, blocking the port will change the frequency response of the speaker. The change may go in a good or bad direction depending on your speaker placement. You'll just have to try it.