Earliest post I can find on this forum that has those expressions is:
Bogdan might have adapted a sed command I suggested for commenting out something in PulseAudio configuration, but I was mostly using simpler sed commands back then
To comment out and disable AUR updates
sudo sed -i 's/CheckAURUpdates/#CheckAURUpdates/g' /etc/pamac.conf
To uncomment and enable AUR updates
sudo sed -i 's/#CheckAURUpdates/CheckAURUpdates/g' /etc/pamac.conf