Although these reports of the lyrics of the song and the meanings of the local vernacular are interesting and informative, I feel there is a point of especial consequence which is glossed over in this focus, and that is this:

The protagonist of the song, this jolly swagman drinking tea and grabbing a passing sheep, FUCKING KILLED HIMSELF, I MEAN WHOLE-ASS COMMITTED SUICIDE BY DROWNING the moment the cops showed up to question him about that goddamned sheep.

No attempt at fight or flight, nor to explain the situation, just a straight-up "Ha!! You'll never catch me alive," and the instant proof thereof.

On a more subtle note, has anybody here ever seen an actual sheep? They are not small animals like a rabbit or a chicken. And "jumbuck" specifically means a recognizably male sheep (hence "buck"), and as with most mammals males are larger than females. Due to its sex-specificity the word is not typically used to refer to a baby sheep, which would simply be a lamb. I mean, it's not impossible that it would be, it's just that it's unlikely that that wouldn't be spelled out. Nor would a more infantile sheep be as likely as a more fully grown one to wander off by itself. And a reasonably grown male sheep will be four or more feet long and well over a hundred pounds (typically over two or three-hundred pounds), so I don't care how jolly this swagman is, if he's stuffing a jumbuck in a tucker-bag, that must be one hell of a tucker bag.

Back to the suicide thing. So the feds show up and sensibly ask "Whose is that jumbuck you've got in your tucker bag?" because obviously swagman hasn't been waltzing matilda with 250+ pounds of sheep on his back for long, and, lets be honest, the g-men know what's going on because they have shown up there with the owner of that especial sheep, so it's really more of a rhetorical question. But the problem with this is, so what? The swagman could have just been honest -- this sheep came wandering by with no sign of a legitimate owner in sight. What's he supposed to do, ignore it? This is Australia, mate, left to wander it will just get eaten by a crocodile or a pack of dingoes. Swagman was really just saving it from falling back to Nature, red in tooth and claw.

Maybe there's more to this story, and really they caught him doing something else, something infinitely more unspeakable, with this sheep, but even then one would have to surmise that the Australian criminal justice system of the day was quite a horrible thing to behold to make immediate suicide (by drowning, which is a sucky way to die, and consequent soggy ghost-duty) preferable to any other alternative which may have been tried in the moment. Either that, or this swagman was already teetering close enough to the edge of mental balance to be pushed over without great provocation.