Context:

nostr:nevent1qqsqcganhegfwj4q533sv8wcezysa23cjfmym8za8ltvel6anzg329qpzemhxue69uhkummnw3ex2mrfw3jhxtn0wfnj7q3qymt2j3n8tesrlr0yhaheem6yyqmmwrr7actslurw6annls6vnrcsxpqqqqqqztn4ufe

In other words, it is a simple means of verifying you are in fact a real person, and not posing as someone you are not, since it would be unlikely you could produce a picture of someone you are impersonating with a shoe on their head.