mental lightweight 

An idiot, a numbskull.

Tim: Look at that person stealing that bag.
Mr M: What a mental lightweight.
Tim: Hey that's my bag.
Mr M: Sucks to be you.

mental lightweight by Eric3831 February 9, 2008

Lockdown Lightweight

Someone who has not consumed any or very little alcohol during lockdown. Then when lockdown has eased they consume alcohol and become drunk very quickly.

"Blimey we are in the pub and Dave has only had 1 beer and he is wobbling all over the place. He has become a lockdown lightweight"

Lockdown Lightweight by Chelle_Belle78 June 1, 2020

Musical Lightweight 

Humans incapable of being able to listen to entire song. Usually getting bored with a every song by the time it gets to half way and moving to the next song.

Isaac: hey Lachlan why did you change the song?
Lachlan: I didn't like it, I was getting bored
Isaac: Gee man, your such a musical lightweight

Samara keeps changing the song, she's such a musical lightweight.

Musical Lightweight by The_Milkman99 November 26, 2014

XM8 Lightweight Assault Rifle 

A 5.56mm assault rifle currently in the developmental stages to replace the M4 Carbine and M16-series weapons, and serve along side the XM-29 (formerly known as the Objective Individual Combat Weapon).

The XM8 is being developed by the U.S. military.

XM8 Lightweight Assault Rifle by JoeBob September 7, 2003

bud lightweight

Someone who can't handle very much "Bud" (Budweiser) or "bud" (marjuana).

Whoa! Mrs. Johnson sure got wasted at that party. What a bud lightweight. She even sucked off Jeff!

bud lightweight by Bud Miller December 1, 2006

Eureka RapidClean Pro Lightweight Cordless Vacuum Cleaner, High Efficiency Powerful Digital Motor LED Headlights, Convenient Stick and Handheld Vac, Essential, Blue 

Efficient Cordless Cleaning: Powered by the latest motor technology the Rapid Clean makes cleaning convenient and thorough
40 Minutes Long Lasting Runtime: Up to 40 min of fade-free runtime. Easily switch to MAX power on fingertip controls to increase suction for better cleaning on carpet and rugs
Easy Rest Feature: Need to take a break? The specially designed Easy Rest nook allows you to safely prop the vacuum up on countertops and furniture
Under Furniture Reach: We moved the dust cup to the front so you can lay the vacuum completely flat to reach under beds and furniture with ease
LED Headlights: Bright beams light the way so you can see dust and debris that might otherwise have been missed and make cleaning under furniture much easier

Oh man, I can't wait to get home and use my Eureka RapidClean Pro Lightweight Cordless Vacuum Cleaner, High Efficiency Powerful Digital Motor LED Headlights, Convenient Stick and Handheld Vac, Essential, Blue to clean my dog's shit.

Eureka RapidClean Pro Lightweight Cordless Vacuum Cleaner, High Efficiency Powerful Digital Motor LED Headlights, Convenient Stick and Handheld Vac, Essential, Blue by SuperSamboy May 29, 2020

intellectual lightweight 

A tiresome individual whom finds it difficult to intelligently think for more than 3 seconds. See Fuckwit and Imbecile.

"Jeremy, you are an intellectual lightweight and a burden on society.".

intellectual lightweight by The harrowing voice of wisdom. November 29, 2015