noun: short for mega chunk. A large chunk of dirt, grass, or other natural material found in drinking water obtained from a river, stream, or other natural water source. Usually found while backpacking or camping
origin: When a group of Pasadena students were on a backpacking trip in the San Jacinto wilderness, they called small pieces of dirt in their water chunks. The large ones were called mega chunks which became m'unks
Oh crap! There's a m'unk in my water!