Mysterious Lump

Master called me from work yesterday, saying he'd be late, and that he had a painful and itchy lump under his arm that he wanted me to look at.  I wasn't thinking much of it, so I went to do errands, and when I got back he was already home.  He was seated at the kitchen table, and said I should come look at his lump now, because it was really bothering him.  I waited for him to take off his shirt.  

He didn't, so I asked if he could.  

"It hurts to lift up my arm, could you just get down there and look under?"

I knelt on the floor, and that is when I saw his pants were covered in blood.  Slightly alarmed now, I peeked up under his shirt, and it looked like he was holding a tan balloon in his armpit!  



"Why do you have a balloon in your armpit?" I asked.  


First thinking he'd totally gone around the bend, I quickly remembered it was April Fool's day. 

Then he took this out: