So my gecko has this stuck in their vent the last 3 days. Is it a sperm plug, prolapse, or something else?? I don't get paid till Friday but I plan on taking him to the vet. Until then I've been soaking him in warm water for about 10-15mins.
Usually sperm plugs are white and prolapses are all red or pink (or black if the hemipenis gets necrotic). You could push gently on the bulge which will cause the hemipenis to pop out. If it's a big sperm plug, you'll see it stuck into the end of the hemipenis and you can just pull it (the plug, not the penis) off. If it seems like pus, or seems to actually be the hemipenis, soak him in a heavy sugar water (i.e. lots of sugar, not so much water) solution, in karo syrup or in human PreparationH. That will shrink the tissues so things can go back where they belong. My bet is on sperm plug because of the color.