call him something that you can't spell/say.
something unpronouncable isn't tha tfunny.
make his name a sound.
[the sound you make when you clik you toungue] woudl be awesome
or name him [an extra long silent pause], so every time you refer to him you have to pause really long and it gets awkward for people not in the know.
or name him the whistle sound, fart sound, clapping twice.