Police in Belgium asked residents not to post messages on social media during the security lockdown, so residents have responded with a slew of cat pictures on twitter - all with the hashtag #BrusselsLockdown.
One user says the very idea of angry, confused terrorists scrolling through the hashtag was making him quite happy.
The highest possible terror alert continues in Brussels today, with schools, universities and the city's metro system all closed.
Police hunting for Paris attack suspect Salah Abdeslam asked residents not to share any information which might tip the terrorists off.
The authorities have responded by thanking Twitter users for their feline contributions.