How does one do a slide?

[JuneSees27]

Oh, that slide? Just use your finger to slide on the string, or if you want it smoother, try using a slide bar (the metal/glass tube)
stickman hook

Thank you, but I was not talking about doing a slide on an actual guitar, as I already know how to do that. I also imagine playing deftones with a slide bar would be quite difficult.