Combination of the word double and the phrase lol, referring to something too amusing for the mere lol and thus calling for the more powerful "doublol". Used most commonly shortly after someone has already replied to a previous statement with the less powerful lol.
Brant: So, I saw Alyssa and Josh earlier, I guess they're dating...
Brant: And somebody told me they were even engaged too...
A double lol. Lolling at two videos at the same time using the new Facebook ticker.
That video you posted and the one your ma posted caused me to doublol.