Juggling stuff ! It helps with dexterity, can be practice alone or with friends, and can be played from 3 years to the death. - Juggling balls (classical or bouncing) - Juggling rings - Juggling clubs - cigar boxes - diabolos - devil sticks - spinning plates - yoyo - Kendama
And after a bit of practice, you can add fire balls, juggling torches or juggling knives !
Btw, about tablets, I suggest to look ones powered by Allwinned A10 chip :-) We had topic not long ago. But never ever buy ones with 800x600 resolution ones.
but back to funny Christmas presents, I remember one year when extended family all drew names from a hat, my weed smoking, booze guzzling cousin drew my grandma's name, and she had been telling everyone that she really needed a "G string" (for her guitar, of course . . . God bless her). I'm sure you can finish this one without too much trouble. Needless to say, everyone got a good laugh out of it.
Buy someone a very nice box and some very expensive looking gift wrap. You dont want them wasting time looking for something to put their gift to you in
I bought my 6 month old nephew an electric piano. Seems random, but for the rest of the family I've been digitizing old family movies, and my sister (nephew's mother) used to think it was funny to make her younger siblings "play" her keyboard.
http://www.thisiswhyimbroke.com has cool nerdy stuff. I'm partial to anything shark-related, like a shark sleeping bag where when you get in it, looks like you're being "eaten" by it. Same for shark socks.
@alcomposer there are fog bubble machines where the bubbles have fog INSIDE them. Got one at work. Also, glow in the dark bubbles at the site above, but I've never seen them myself.