by readstories1989
“Slept like a pig” is not an English phrase.
In English, we sleep like a Baby (an innocent sleep, of wonder and contentment). Or we sleep like a Dog (from exhaustion and hard work).
One can also sleep like a bear (as if hibernating for the winter). And obviously one can sleep like a drunk (even if you are buzzed from something other than alcohol, like love or sex). Get it?