Every 3 minutes for as long as possible complete:

From 0:00-3:00

   2 rounds of:

   10 overhead squats

   10 chest-to-bar pull-ups

From 3:00-6:00

   2 rounds of:

   12 overhead squats

   12 chest-to-bar pull-ups

From 6:00-9:00

   2 rounds of:

   14 overhead squats

   14 chest-to-bar pull-ups

Etc., following same pattern until you fail to complete both rounds