ONE-UPPING My girlfriend and I often laugh about how competitive we are. But I laugh more.
Source:reddit.com
What is the point of the joke? Please explain it to me.
He and his girlfriend are both pretty competitive persons, which means they want to win more than (almost) everything. He says that they both laugh about it.
The joke is in the:
But I laugh more.
Meaning that even when it comes to laughing about their competitiveness, the person wants to be the one laughing more, to win the "laughing contest", due to him being competitive.