well if your male is producing plugs some people remove them and put the male in with a female , cause once the plugs are gone he's free to breed ..

ok best way i can think of for a visual to what it would be like
(lol it may not be the best refference but im sure it will give you a picture)

think of a cut off garden hose , now roll up some papertowels and shove it in the opened end of the hose , think of the paper towels as the plug and the hose is the skin or shaft around the hemi's , the hemi's wont pop out while the plugs there until either its been removed or they fall out ..

i had a couple males that produced plugs and i pulled them out . if i had thought about it as a tutorial before hand i would have snapped some pics to help . but sorry i didnt take any .