QUOTE(freudia @ Nov 17 2015, 00:30)

くちゅっ is described as a wet smacking sound by Tonigobe, but The Jaded Network gives "rub, stroke, fondle" as the meaning. The latter seems to make more sense in that context.
Tonigobe is closer to the real meaning, if you ask me: くちゅっ is like this kind of wet suction / sucking / wet contact sound. I can't remember for Tonigobe (because I haven't used the guide in ages), but I think some of the translations on The Jaded Network are just way too vague, and sometimes quite far from what the sound actually means.