Since I am from Scotland I think a scottish accent would be funny and I will run by you some funny phrases that could be said.
When ordered to do something: "och aye capn"
When shot : "ah ya dirty ***"
when engaging covenent" yer maws got baws ya bunch o alien bastards"
There are many more but some of these funny phrases could be unlockable e.g. skulls.
No point in running away cos i`ll just snipe you.