The generous spread of chubby fat on the body parts that are not covered with clothing, like in the neck area or calfs/thighs or triceps. Usually associated with obese people. A muffin top can be considered a part of chubbery.
Example : His dad got some serious chubbery surrounding his face. They better work on his diet!
When a guy is turned on, but not quite ready to grab a couch pillow to awkwardly conceal his arousal- an erection that is safe for public consumption- i.e. not pitching a tent, but beginning to feel aroused.
When that girl with thatfine ass bent over right in front of me to adjust the spoke nipples on her Fuji bicycle, I chubbed up a bit.