Being a judge in a hackathon is one of the criterion for O-1 visa.
https://www.linkedin.com/pulse/getting-o-1-visa-easier-than-...
Actual regulation is:
Evidence of the alien's participation on a panel, or individually, as a judge of the work of others in the same or in an allied field of specialization to that for which classification is sought;[1]
is one of eight criterion (of which meeting three is required).
Examples given by USCIS[2] are:
Examples of relevant evidence may include, but are not limited to:
Reviewer of abstracts or papers submitted for presentation at scholarly conferences in the respective field;
Peer reviewer for scholarly publications;
Member of doctoral dissertation committees; and
Peer reviewer for government research funding programs.
Which seems to indicate rather more prestige than “judging a hackathon” is the intent of the regulation.
[1]: https://www.ecfr.gov/current/title-8/chapter-I/subchapter-B/...
[2]: https://www.uscis.gov/policy-manual/volume-2-part-m-chapter-...
