I have two eight year old male cats. I was playing with one of my cats and noticed a new bump I've never seen before by his stomach. I thought it was something stuck on him as it was protruding and I couldn't get it off. These are the only cats I've ever had and I've no experience with ticks or anything of that nature so I got concerned.
I go to check my other cat in the same areas and I found a similar bump that I couldn't get a close look at. I panicked and called the vet and he told me to bring them in.
Now I'm short on money so I had to scrape together hundreds of dollars and rush them to the vet to get looked at. They're vet anxious so I first needed to pick up some medication then give it to them then take them a few hours later.
We do the whole process and get them in the crates and eventually get them to the vet. I finally take them inside and I'm trying to show the vet and vet tech where the bumps are. After a little searching I find it and point it out. All of a sudden the vet and vet tech start laughing hysterically.
Turns out I had found my cats' nipples. The vet took some pity on me and gave a discount for this very important lesson: male cats also have nipples.
TL;DR: found bump on both my cats' stomach and rushed them to the vet to get checked. The bumps were nipples.