Banach spacers do it completely. Bayesians do it with improper priors. Catastrophe theorists do it falling off part of a sheet. Chaoticians do it with sensitive dependence. Class field theorists do it by capitulation.
Classical geometers do it with a straight edge.
Classical geometers do it from the right angle. Combinatorists do it discretely. Combinatorists do it as many ways as they can. Commutative algebraists do it regularly. Complex analysts do it between the sheets.