A scrotum, (the pouch of skin that holds the testes), but very small in size. A skalum is typically at least half the size of the average scrotum.
The word skalum originated in Philadelphia, PA, at a pharmaceutical company. It is a combination of a former computer support employee's last name and scrotum. He was a tiny man, and his scrotum was minuscule. Hence, a "skalum".
"I was feeling like a stud until she laughed at my skalum".
"When it's cold outside, you can't even see my skalum!"
Prices shown in USD.