Headcanon that Freya and Arthur become afterlife BFFs in Avalon, and even though they can't return to the living world, Freya can visit, as long as she doesn't leave the lake, and this is how she and Arthur learn about the modern world, including language. Particularly slang. Not all of it is exactly accurate (think Ariel and the dinglehopper) but they're learning.
Stuff left on the docks? Gone. Too close to the shore? Yoinked. Things dropped in the lake? Never recovered. She even takes stuff from boats because technically she's still in the lake.
Freya, rollerskating into Avalon wearing a beach towel like a cape and a pair of giant sunglasses, carrying a boombox and a cooler of beer: Arthur, my good bitch, you will not believe what I found this time.
Arthur, wearing a 'Sun's Out, Guns Out' tank top, jean shorts, and a huge sunhat, reading one of the three dozen trashy romance novels Freya's brought him, drinking a pina colada through a crazy straw: Oh, word?
Percival: When I said you should try being friendlier, this isn't what I meant.
Gwaine, stirring a cup of tea annoyedly: Oh, so now I'm too friendly? There's no pleasing you, Percival.
A bandit, who broke into the castle an hour ago: Two sugars, please.
Gwaine: here you are my friend
Arthur: So, it's the first week of the new year. How's everyone doing?
Morgana: I crave murder.
Gwaine: I've concocted a drink that lets you go for five full days without sleep!
Elyan: Or so he claims. It has coffee, three different energy drinks, and five shots of espresso.
Merlin, twitching violently: I'VE TESTED IT. IT WORKS.
Gaius: I'm recording the progress of Merlin's slow but inevitable death.
Morgause, on the phone: Hi, my idiot brother chased a cat and is stuck in a tree.
Fire department: Sorry, right now we’re only responding to fires.
Morgause: I see.
Morgause:
Morgause: Give me a second.