Touchdown!

Touchdown! is an achievement/trophy in Fallout 4.

Requirements
Score a touchdown.

The player needs to be killed by a nuclear explosion, either the super mutant suicider's explosion or by a Fat Man in order to get this achievement. This also appears to occur when your companion is "kneeled" by a nuclear explosion.

Behind the scenes
The name "Touchdown" refers to the suicide mutant's act of throwing the nuke on the ground like football players are known to do when celebrating a touchdown.