Clad in a sleeveless brown shirt that displayed his many upper-arm tattoos, the charming blues-pop singer looked every bit the festival leader, particularly as swooping crane shots revealed the ***undulating crowd*** on giant video screens. http://74.125.95.132/search?q=cache:HvY7OFpB86EJ:www.denverp...

A vast, undulating crowd waits for the show to begin. http://artlog.com/events/2373-mark-shetabi-arena

And, of course, a jury reasonably could think that hand baggage of assorted size, shape, and weight on the floor alongside, or in front of, a group of passengers loosely lined up several abreast might cause people to stumble, lose their balance, trip or fall as the ***undulating "crowd"*** of people slowly move forward or backward in the course of beginning, or making, or concluding air travel. http://74.125.95.132/search?q=cache:XTADmMYwx2YJ:openjurist....

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Note added at 7 hrs (2009-07-27 17:33:04 GMT)
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Your sentence would read: at the hotel entrance [...] a whole crowd was undulating with laughter.

Example: Duerma giggled, her whole little body undulating with laughter. http://corrienda.livejournal.com/

We pulled the bushes aside and spotted Blaustein flat on his back with his big belly undulating with laughter. http://books.google.com/books?id=DNkmw30tbrYC&pg=PA119&lpg=P...