They recently turned 3, and are just so cute right now. While their language skills are a little behind, they certainly make up for it in exuberance.
Here's how it goes: P will hide somewhere (usually while JP is watching LOL), and then JP will say "me 1, 4 5" (meaning I'm going to count now). He then runs away to a different room and counts to 10:
"1, 4, 5,6, 8,9, 10! ME COME!!"
P giggles in anticipation in the other room, while JP runs to where he's hiding and yells triumphantly,
Then they trade places and repeat the whole process 5 or 6 more times, usually using the exact same hiding spot. This can keep them occupied for a good 30 min or so, and they've been doing it a few times each day for the last week since their big brother taught them how to play.
I'll try to get a video of it next time they do it, because it's just so cute. Problem is, they are both usually missing at least one important item of clothing, so I'm not sure they'd appreciate me posting it on the internet :-)