1. A person, often an acquaintance, who is vaguely annoying or a bit of a boring bastard.
2. A task which will be tedious or will take a long time.
3. Something which is, literally, lengthy.
4. Comedy euphemism for the penis.
Note similarities with urban slang such as long
1. "I don't wanna hang out with that longmate!"
2. "Nah, forget it man, it'll be longmate."
3. "I had to walk up this longmate road."
4. "I showed her my longmate."