I went a different route, and not being in possession of a foursquare account, this is untested. I went with LWP instead:
Update: I guess since LWP is 'non-standard', this doesn't qualify</shrug> 
#!/usr/bin/perl
use LWP::UserAgent;
sleep(rand()*600);
my ($lt, $lg) = map { $ARGV[$_]+rand()*0.0001-0.00005 } 1..2;
my $lwp = LWP::UserAgent->new(agent=>'Mozilla/5.0 (iPhone; U; CPU like
+ Mac OS X; en) '.
'AppleWebKit/420+ (KHTML, like Gecko) Version/3.0 Mobile/1C10 Safari/4
+19.3');
$lwp->default_header(Authorization => 'Basic XXXXXX');
$lwp->post('http://api.foursqure.com/v1/checkin', {vid=>$ARGV[0],priva
+te=>0,
geolat=>$lt,geolong=>$lg});

[download]

And the slightly better looking version: 
#!/usr/bin/perl
use LWP::UserAgent;
sleep( rand() * 600 );
my ( $lt, $lg ) = map { $ARGV[$_] + rand() * 0.0001 - 0.00005 } 1..2;
my $lwp
    = LWP::UserAgent->new(
    agent => 'Mozilla/5.0 (iPhone; U; CPU like Mac OS X; en) '
        . 'AppleWebKit/420+ (KHTML, like Gecko) Version/3.0'
        .' Mobile/1C10 Safari/419.3'
    );
$lwp->default_header( Authorization => 'Basic XXXXXX' );
$lwp->post(
    'http://api.foursqure.com/v1/checkin',
    {
        vid     => $ARGV[0],
        private => 0,
        geolat  => $lt,
        geolong => $lg
    }
);

[download]

In reply to Re: Nine-line Perl example of gaming a geolocation service and an open invitation to golf it by james2vegas
in thread Nine-line Perl example of gaming a geolocation service and an open invitation to golf it by mr_mischief

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