Why would a plane need to do a couple of 360’ turns on the taxi way/run-up area. The crew were given clearance to taxi and hold. They told the tower they needed to turn the plane 360’ and were cleared. When they asked for a second 360 they said they were trying to resolve a fuel imbalance issue. I think this was a Gulfstream. What was going on with this.
They probably had a fuel imbalance that was marginally outside the limit for takeoff, and perhaps the powered fuel transfer system was unserviceable and was deferred. Typically there is a gravity transfer capability by just opening a transfer valve and letting fuel run across on its own with the imbalance present, or by skidding slightly.
If they were say 50 or 100lbs above the max lateral imbalance for departure, a spin around on the ramp a couple times with the gravity transfer valve open so that some fuel "sloshes" through the gravity transfer line to the opposite tank, due to the centrifugal force of the turn, may have been enough to get the value in limits.