I.up [美 əp, 英 ʌp]副up often appears as the second element of certain verb structures in English (back up, pick up, sit up, etc). For translations, see the relevant verb entry (back, pick, sit, etc).
That'll allow him to more easily channel away water in advance of hurricanes or other storms, so that the ground can then sponge up more when the deluges come.
The reason sticky friction is the most important friction is because it lets the player really sponge up the (in-game) reality of the awesome thing he just did.