i think it depends who the 'person' or 'other people' is lor...
if is ur bf / gf, maybe can bite each other's nails???

constructively, places / things for couples to do, so many in SG. u're limited by ur imagination and creativity.

Go labrador park fishing / walk walk / pig-nick
Go ubin cycling, drink coconut juice
Go camping / setup a tent @ east coast
Go trekking in Macritchie to the tree top walk, walk from bukit timah to macritchie thru the forest (i did dat!)
Go pandan reservoir and run / cycle 2 rounds
Go genting and relax for 2 d 1 n .. $69 oni...
Go sungei buloh see lazy birds
Go zoo take photo
Go botanic garden sit down under tree and pig-nick, read newspapers
Go turf city look at jap race queens, then proceed to toilet
Go midnite shopping at suntec city while GSS still on
Go download BT of all the movies u never watch but wanted to, and watch @ home
Go borders read books and gain GK and self improve
Go read magazines there too.
Go learn and do those things u wanted to do but didn't have time to before (since now u have so much time to say that you've can't think of anything nice to do )

see! so many... hopefully a few of the above is useful.