The pair were understood to have received an on-the-spot fine by police for urinating on a shop front in Manly at around 9.30pm on Sunday night.
The pair will miss the Sea Eagles’ clash against Cronulla on Saturday.
Manly CEO Graham Lowe said the behavour of the players was unacceptable.
“They have embarrassed themselves and the club and its sponsors and supporters – they have shown great remorse for their silly action and will pay a heavy penalty,” Lowe said.
Watmough and Seuseu offered the following joint statement:
“We are bitterly disappointed with our actions and for the fact that we have let our team mates, our families and our supporters down.
“It was a careless and stupid thing to do and we accept the suspension without complaint.”