Steel workers do it hotter. Stewardesses do it in the air. Stock brokers do it on the margin. Stragglers do it in the rear. Structured programmers do it repeatedly or else.
Students use their heads.
Supercomputer users do it in parallel Superman does it faster than a speeding bullet. Surfers do it standing up. Surgeons do it incisively. Swimmers do it in the water. Swimmers do it under water.