I am going to answer this assuming that you aren't trolling, that said this is a very strange question.
I would not advise letting any conductive liquid make contact with any part inside your PC. Sooner or later you are going to short circuit something. Symptoms could range from graphical glitches to your card being completly broken, do not spit on your PC!!
Gaming rig - P8-Z68 PRO/ I5 2500k @4.2ghz / 650W antec trupower PSU/ 8gb vengeance /120gb OCZ agility 3/ 1TB F3 HDD/ 2TB F4 HDD/ GTX 560 TI OC/ HAF X/ Arctic cooling freezer 13 pro/
Lappy - Dell XPS17/ 740QM/ 8gb ram/120GB agility III/ 750gb WD 7200rpm/ GT445m/