My guess is that it's describing someone heavily drunk and about to collapse (2 second from collapsing). The back-and-forth and side-to-side lurching motions can look undulating and liquid-like.

"Undulous" would be from "undulate" which is the motion of waves. It's the image of someone heaving as a reflex action, such as a person who is crying uncontrollably and has a hard time breathing, or someone who is about to vomit. In the context of a wedding, I think "bubbling" may be a typo for "blubbering". Blubbering is the action of crying uncontrollably.