Tapping up is the attempt to crack onto somebody, not necesarily involving intercourse, maybe just a cheeky pull. It can also can be used in the context of failure.
"Tim tried to tap up that girl last night but failed"
Hertford College tərəfindən 15 May 2008
1 more definition
An English slang word word meaning a bribe
"If you need to get your motor through it's MOT just tap up Bill and he will sort you out"
Darrenwl tərəfindən 07 Fevral 2007