in sg its illegal to be in large groups.
To be more specific :
Unlawful assembly.
141. An assembly of 5 or more persons is
designated an “unlawful assembly”, if the common object of the
persons composing that assembly is — (a) to overawe by criminal
force, or show of criminal force, the Legislative or Executive
Government, or any public servant in the exercise of the lawful
power of such public servant; (b) to resist the execution of any
law, or of any legal process; (c) to commit any offence; (d) by
means of criminal force, or show of criminal force, to any person,
to take or obtain possession of any property, or to deprive any
person of the enjoyment of a right of way, or of the use of water
or other incorporeal right of which he is in possession or
enjoyment, or to enforce any right or supposed right; or (e) by
means of criminal force, or show of criminal force, to compel any
person to do what he is not legally bound to do, or to omit to do
what he is legally entitled to do. Explanation.
An assembly which was not unlawful when it assembled may
subsequently become an unlawful assembly.
On a side note, the amount of people no longer applies. Any
amount of people could also be considered an "illegal
gathering."