M Huncho ft Nafe Smallz- Thumb

This from UK rapper M Huncho featuring Nafe Smallz from Skepta's 'Greaze Mode' fame which entered the UK Top40 on Friday at #30. This becoming M Huncho's 2nd UK Top40 hit and Nafe Smallz's 3rd UK Top40 hit.

What do you make of this from the balaclava-wearing rapper?

'Thumb' seems to be about this:

Put my thumb up in her butt"