Another trick is hidden dividend accrual for preferred stock. The dividends are triggered at liquidity event, so the cap table you thought you were looking at suddenly gets diluted with a bunch of freshly issued stock which is still senior to common.
From reading "Venture Deals" I got the impression it's something a big VC firm tries to negotiate on a fairly regular basis. See, for example, the "Dividends" section of Houzz round http://techcrunch.com/2014/06/02/houzz-on-fire/
