Bottomelon is when a girl is wearing a thong in a skirt that sometimes rides up showing the bottom part of her butt cheeks. This makes her butt look like two melons are hanging out from her skirt.
A hardo is a person who tries extremely hard at everything. Most times a hardo will try very hard at things that do not require excessive effort. For example, sports practices, gym class, etc.
Wow did you see Jack at practice today? What a hardo!