This question about zip bombs naturally led me to the Wikipedia page on the topic. The article mentions an example of a 45.1 kb zip file that decompresses to 1.3 exabytes.>
Recent (post 1995) compression algorithms like bz2, lzma (7-zip) and rar give spectacular compression of monotonous files, and a single layer of compression is sufficient to wrap oversized content to a managable size.
Another approach could be to create a sparse file of extreme size (exabytes) and then compress it with something mundane that understands sparse files (eg tar), now if the examiner streams the file the examiner will need to read past all those zeros that exist only to pad between the actual content of the file, if the examiner writes it to disk however very little space will be used (assuming a well-behaved unarchiver and a modern filesystem).