Helium...
That's me, breathing helium, and laughing too much to speak...
(my friends behind the camera didn't exactly help, and just kept on telling me to breathe in more...)
(that green bunny is not something from Silent Hill but actually the symbol of Liseberg, the amusement-park we were at)
Part 2, with more talking (and less talking) is here; • heluim (part 2)