code/controllers/subsystem/verb_manager.dm

/var/SSverb_manager	SSverb_manager, a subsystem that runs every tick and runs through its entire queue without yielding like SSinput. this exists because of how the byond tick works and where user inputted verbs are put within it.
/proc/_queue_verb	queue a callback for the given verb/verblike proc and any given arguments to the specified verb subsystem, so that they process in the next tick. intended to only work with verbs or verblike procs called directly from client input, use as part of TRY_QUEUE_VERB() and co.