well, if I am bouldering near a lake or river, it would typically mean 'fish on'.
However, in the parlance of street slang, tight = cool, good, badass, awesome, favorable, sooper dooper.
when I use it, it means fucking brilliant powerful lines that will make you weep, shortest distance between start and finish stuff, no traversing, no rope clipping or hangdog dabbing and no whipping, pendulum swinging or faggoty french footwork.
you know, 100% pure manly stuff.