This is my favourite. “Faffing” has no proper equivalent in N. American parlance. “Wasting time” and “goofing around” do not express quite the same thing. Faff: To muck about, “dither or fuss” (from dictionary.com).
2. “Muck in”.
“To share in work that needs to be done” (Collins Dictionary online).Â “Muck” (dirt) has vaguely unpleasant connotations – much like helping a friend with a boring task like painting a house.Â “Pitch in” doesn’t have quite the same effect, and can even suggest the transfer of money rather than services.
“Naff” means uncool, tacky, unfashionable.Â The closest equivalent is probably “kitsch”, but I can’t think of an equivalent N. American term that communicates so many things so precisely.