My S4 team basically had a theme song of 'what doesn't kill you', so before going to warmups, we would always just go crazy in our little area dancing to this song. If we had a good warmup, then once we were done with the final mat, if there was extra time we'd do what we call 'turkeys'. 'I went down to the water!...and I took a little walk...and I met up with some turkeys....and we had a little talk...so I washed them turkeys...and it had a few other lines & arm/leg movements. lol we always looked like absolute idiots yelling it in the warmup room.
Im not sure if this would be considered a 'ritual', but it's just something my gym's done for a while. We have one designated person who calls 'ready!' and we have some cute way of saying our team name. Like for black diamonds we put out a ring finger.