A man with a large penis and massive testicles A jumbo Jet refers to the fact that the owner of the afore-said jumbo sized tackle is able to force a correspondingly large amount of semen from it during ejaculation
slapper:
Fuckin ell that were a feller I had last nightlet me tell ya! That were a proper fuckin jumbo jet I ad flying into my terminal 5 last night
Jake: 'That bird is well fit.'
Toby: 'You're not wrong there - she's jumbo tonk.'
or
Jake: 'Whoa dude, don't tell me you managed to slam the new jumbo tonk hairdresser from downstairs?'
Toby: 'Let's just say, "She got her's - for sho.'"